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VOL. XV NO. 1 

JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 




JULY, 1930 



PUBLISHED MONTHLY, AT EASTON, PA., BY THE 
SOCIETY OF MOTION PICTURE ENGINEERS 



The Society of Motion Picture Engineers 

Its Aims and Accomplishments 

The Society was founded in 1916, its purpose as expressed in its 
constitution being "advancement in the theory and practice of mo- 
tion picture engineering and the allied arts and sciences, the standard- 
ization of the mechanisms and practices employed therein, and 1 
maintenance of a high professional standing among its members. 

The Society is composed of the best technical experts in 1 
various research laboratories and other engineering branches o 
industry in the country, as well as executives in the manufacturing 
and producing ends of the business. The commercial interests als< 
are represented by associate membership in the Society. 

The Society holds two conventions a year, one in the spring and 
in the fall, the meetings being generally of four days' duration each, 
and being held at various places. At these meetings papers are pre 
sented and discussed on all phases of the industry, theoretical, tech 
nical, and practical. Demonstrations of new equipment and methoc 
are often given. A wide range of subjects is covered, and many of t 
authors are the highest authorities in their distinctive lines. 

Papers presented at conventions, together with discussions, 
contributed articles, translations and reprints, abstracts and abridge- 
ments, and other material of interest to the motion picture engineer 
are published in the Journal of the Society. 

The publications of the Society constitute the most complete ex- 
isting technical library for the motion picture industry. 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 



LOYD A. JONES, EDITOR pro tern. 



Volume XV JULY, 1930 Number 1 

CONTENTS 

Page 
Technical Activities of the Academy of Motion Picture Arts and 

Sciences IRVING THALBERG 3 

Talking Pictures The Great Internationalist 

HAROLD B. FRANKLIN 17 

The Revolving Lens Wheel Projector ARTHUR J. HOLMAN 20 

A Microphone Boom ELMER C. RICHARDSON 41 

Tilt Heads and Rolling Tripods for Camera Blimps 

ELMER C. RICHARDSON 46 

Volume Control by the Squeeze Track. . .WESLEY C. MILLER 53 
The Measurement of Light Valve Resonance by the Absorption 

Method O. O. CECCARINI 60 

Progress in the Motion Picture Industry 68 

Abstracts 124 

Book Reviews 128 

Officers 129 

Committees 130 

Chicago Section 133 

London Section 133 

New York Section 133 

Pacific Coast Section 134 

Society Notes 134 

Wanted An Editor-Manager 135 

Constitution 136 

By-Laws 137 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 
Associate Editors 



G. L. CHANIER P. MOLS S. E. SHEPPARD 

O. M. GivUNT W. B. RAYTON J. L. SPENCB 

A. C. HARDY P. E. SABINE L. T. TROI.AND 



Publication Office, 20th & Northampton Sts., Easton, Pa. 
Editorial Office, 343 State St., Rochester, N. Y. 



Published Monthly 



Copyrighted, 1930, by the Society of Motion Picture Engineers 



Subscription to non-members $12.00 per year; single copies $1.50. Order from 
the Secretary of the Society of Motion Picture Engineers, 20th and Northampton 
Sts., Easton, Pa., or 2 Clearfield Ave., Bloomfield, N. J. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Application pending for second-class entry at the Post Office at Easton, Pa. 



TECHNICAL ACTIVITIES OF THE ACADEMY OF MOTION 
PICTURE ARTS AND SCIENCES 

IRVING THALBERG* 
I. INTRODUCTORY 

In the latter part of 1929, the Board of Directors of the Academy 
of Motion Picture Arts and Sciences, acting at the suggestion of the 
Producers' Branch, launched two major projects for the general 
technical benefit of the production industry. The first of these 
projects was the establishment of a school for the education of studio 
personnel in the fundamentals of sound recording and reproduction. 
The second was the organization of a Producers-Technicians Com- 
mittee for the conduction of a group of new technical activities. 

II. ACADEMY. SCHOOL IN SOUND RECORDING 

The coming of sound, revolutionizing as it did the technic of mo- 
tion picture production, created a severe production problem in 
its effect on the studio personnel. The need of internal coopera- 
tion on each lot was never greater; yet the possibilities and limita- 
tions of the new equipment and technic were alike a mystery to the 
regular employees, who thus found their hands tied for effective 
cooperation with one another and with the handful of sound experts. 

The traditional policy of the production industry, particularly 
in technical matters, has always been strongly competitive. The 
introduction of sound naturally served to bring out more sharply 
than ever this policy of competition and secrecy. Nevertheless, 
the internal problem described above was so acute that the producers 
and technicians of the whole industry decided, through the Academy, 
on a bold step toward its solution. This step was the creation of 
the Academy School in Sound Recording. 

Determined to make this project perfect in execution, the Academy 
secured as instructors for the course the cream of the world of sound 
experts heads of studio sound departments, crack engineers of 

* Metro-Goldwyn-Mayer Studios, Culver City, California. (Read before the 
Society at Washington.) 



4 IRVING THAUBEJRG [J. S. M. p. E. 

the electrical service companies, and leading physicists of the local 
universities. Ambitious to secure a technical education from this 
group of authorities, studio employees of all ranks and departments 
applied for admission to the School. To date a picked lot of this 
personnel, nine hundred in number, selected by the studios them- 
selves, have attended the courses of lectures, which have been given 
in six sections. 

We feel that we cannot emphasize too greatly how much this 
project has advanced the general welfare of the industry. It has 
"sold" the whole industry on the vital principle of cooperative in- 
dustrial education. It has given the personnel an unparalleled 
opportunity, which they have seized to the utmost, to do both them- 
selves and the industry a service, not only for today but for the 
years to come. They have received a technical training not confined 
to the methods of their own studios, nor to a few narrow principles 
of application, but embracing the entire known technic of sound 
pictures from scientific fundamentals to all methods of recording 
and reproduction. The lectures were held from studio to studio, each 
section of the class being carefully drawn from the men and women 
of all studios, ranks, and departments; and this has served to de- 
velop in all of them a realization of common interests, and a wide- 
spread comradeship. The technical leaders of the industry, too, 
have been drawn together, by cooperation in administering the 
course. The monetary value of all these services of the School in 
contributing to industrial education, cooperation, and morale, is 
beyond computation. 

III. THE PRODUCERS-TECHNICIANS COMMITTEE 

Side by side in industrial progress with the creation of the Sound 
School, that of the Producers-Technicians Committee has already 
been referred to. It was the purpose of this committee to con- 
duct such specific technical activities as would benefit from coopera- 
tive investigation, experimentation, and pooling and distribution 
of information. In this work the committee had as precedent 
the broad survey of the problem of incandescent illumination which 
the Academy (with the cooperation of the American Society of Cine- 
matographers, the Association of Motion Picture Producers, and 
your Society) conducted in 1928. This survey, as will be remem- 
bered, served to advance the technic of production very materially, 
and did so, moreover, at the most propitious possible time when 



July, 1930] ACTIVITIES OF THE ACADEMY 5 

sound pictures, which of course promoted the use of incandescents 
(as being in general more silent than arcs), were springing into life. 
It thus served to demonstrate to the industry the value of technical 
cooperation, and particularly the logical function of the Academy 
in promoting such cooperation. 

The Producers-Technicians Committee, created to forward this 
function, is constituted as follows: 

Representing the Producers' Branch: 

IRVING G. THALBERG Metro-Goldwyn-Mayer Studios, Chairman 

FRED W. BEETSON Association of Motion Picture Producers 

M. C. LEvEE Paramount Studios 

WILLIAM SISTROM RKO Studios 

WALTER L. STERN Universal Studios 

H. KEITH WEEKS Fox Hills Studios 

SOL M. WURTZEL Fox Studios 

Representing the Technicians' Branch: 

J. A. BALL Technicolor Studios 

H. G. KNOX Electrical Research Products, Inc. 

FRED PELTON Metro-Goldwyn-Mayer Studios 

GERALD F. RACKETT Society of Motion Picture Engineers 

J. T. REED United Artists Studios 

FREDERICK M. SAM MIS RCA Photophone Corporation 

NUGENT H. SLAUGHTER Warner Brothers and First National Studios 

From the staff of the Academy: 

FRANK WOODS, Secretary of the Academy, Ex-Officio 

LESTER COWAN, Assistant Secretary of the Academy, Committee Secretary 

IV. INITIAL PROJECTS 

The first purpose of the committee was to engage in the investi- 
gation of various technical problems which are primarily non-com- 
petitive. Six such problems have been taken up: (1) silencing of 
arc hum; (2) silencing of cameras; (3) acoustic properties of set 
materials; (4) release print quality; (5) release print standardiza- 
tion; (6) screen illumination. The general procedure in attacking 
these problems was to appoint a subcommittee for each of them. 
The subcommittee conducted a thorough survey of existing methods 
of meeting the problem, conducted tests to determine quantitatively 
the worth of these various methods, and made final recommenda- 
tions for their improvement. These activities were conducted with 
the cooperation of representatives especially appointed by each 



6 



IRVING THAI.BERG 



[J. S. M. P. B. 



studio to aid the work. Full publicity was given to all phases of 
the work by the issuance of progress reports and final reports. 
The history of each of these projects will now be summarized; the 




FIG. 1. Oscillograph records of commutator ripple. 



July, 1930] 



ACTIVITIES OF THE ACADEMY 



full subcommittee reports are available to members of the Society 
of Motion Picture Engineers or to any other interested parties. 

IV- A ARC Silencing. Mr. L. E. Clark, of Pathd Studios, acted 
as a subcommittee of one in investigating this problem. The high- 
frequency hum of arcs, due to the commutator ripple of the d. c. 
generator, has from the beginning been an obstacle to proper sound 
recording. Whenever the studios wished to use arcs instead of in- 
candescents, they were forced to use various devices to filter out this 




FIG. 2. Inductance coils placed at the arc. 



hum; and these devices, as the subcommittee's preliminary survey 
of them revealed, have varied greatly in design, efficiency, and ex- 
pense. The next step in the investigation was to obtain oscillograph 
records of the commutator ripple in each studio generating system 
(see Fig. 1) ; these tests were conducted with the cooperation of the 
Los Angeles Bureau of Power and Light. They revealed that the 
ripple frequencies ranged, in the various cases, from 750 to 3300 
cycles, with a maximum amplitude of 2.7 per cent of the d. c. voltage. 



8 IRVING THALBKRG [j. s. M. p. E. 

Quantitative tests of the various filtering devices were next begun; 
but it was soon found that one device, developed by Mr. Walter 
Quinlan of the Fox Film Corporation (a studio which had great 
preference for the use of arcs), was apparently sufficient for all studio 
needs, from the combined standpoints of efficiency and economy. 
A filter for such a ripple can be of three sorts: (1) a condenser 
across the mains; (2) an inductance in the mains; (3) a combina- 
tion of the two. The first type is in general undesirable because 
its efficiency varies inversely with the load. The use of a single 




FIG. 3. Electrolytic type of condenser. 

large inductance coil is impracticable because of the vast weight 
required. Small inductance coils placed at the arcs themselves, 
however, are quite practicable. (See Fig. 2.) They have small 
weight, volume, and heating loss; and they provide protection at 
each lamp, which in itself is a long step toward keeping feed-back 
noise out of the system. 

The use of inductive filters alone, however, is not sufficient if 
efficiency at light as well as heavy loads is desired. It is necessary 
to use condensers across the mains in combination with such coils. 



July, 1930] 



ACTIVITIES OF THE ACADEMY 



9 



Mr. Quinlan succeeded in developing, for this purpose, a type of 
electrolytic condenser (see Fig. 3), of 1000 microfarads capacity, 
able to withstand 150 volts, able to serve at least ten months when 
properly cared for, without re-servicing, and cheap in price. (This 
condenser is described in detail in Mr. Clark's report.) The combi- 
nation of 2 to 4 such condensers across the generator, and as many 
40 ampere coils at each arc as required, serves, at a cost per generator 
of about $750, to reduce the arc hum about 25 db. which is an ample 
amount. 




FIG. 4. A silencing camera cover. 

IV-B Silencing of Cameras. The problem of silencing the camera 
was investigated by a subcommittee whose members were Messrs. 
H. G. Knox, Vice-President of Electrical Research Products, Inc., 
and Frederick M. Sammis, General Representative of the Pacific 
Coast for RCA Photophone Corporation. This subcommittee, 
assisted by studio representatives, first secured complete data on 
the use in each studio of booths, blankets, blimps, the two principal 
cameras, motors and covers, drives, and minimum camera-micro- 
phone distance. The silencing devices and the cameras themselves 
were then subjected to quantitative noise tests in the laboratories 



10 



IRVING THAL,BERG 



[j. S. M. p. E. 



of Electrical Research Products, Inc. The best devices were then 
retested, primarily for the purpose of determining what construc- 
tional details were inherent in any good device. It was found that 
the silencing value of the different devices varied tremendously, 
from 21 to 11 db. for rigid devices, and from 14 to 1 db. for semi- 
rigid coverings; so, to an even greater extent (20 to 4 db.), did the 
noise from the uncovered cameras. 




FIG. 5. A silencing camera cover. 

The subcommittee then established standards for the desired 
camera silence, varying from studio close-ups to location work; 
and prepared a list of the fundamentals which should be embodied 
in any camera silencing device, together with a list of recommended 
materials for certain purposes, and photographs (see Figs. 4-6) 
showing desirable types of construction, some of which types can be 
embodied in the present silencing devices if desired. As regards 



July, 1930] 



ACTIVITIES OF THE ACADEMY 



11 



the problem of the noisy camera itself, the subcommittee sought 
the cooperation of Mr. G. A. Mitchell of the Mitchell Camera Cor- 
poration. Mr. Mitchell offered to take a noisy camera and over- 
haul it mechanically; and in doing so he reduced its noise from 18 
db. to 12 db., an improvement of 6 db. Mr. Mitchell also tried out 
a new model silent camera which, in the experimental form sub- 




FIG. 6. A silencing camera cover. 

mitted, had a noise of only 1 db. 5 db. less than any Mitchell 
camera previously tested. 
A complete report of the subcommittee's work is now in print. 

IV-C Set Materials. A subcommittee, consisting of Mr. J. P. 
Maxfield and Mr. Ralph Townsend, was appointed to test and classify 
according to their acoustic properties typical materials commonly 
used in set construction for sound pictures. The measurements 



12 IRVING THALBERG [J. S. M. p. E. 

obtained have made available for the first time specialized data of 
practical application to studio conditions. Absorption coefficients 
at typical frequencies were obtained for the following materials, 
erected as in set operation: veneered flats (papered with crepe paper 
and additionally with hard wall paper) ; 7 /i 6 inch Masonite (papered 
with crepe paper and additionally painted with flat oil paint); 
7 /ie inch Celotex (papered with crepe paper and also with one coat 
of water paint) ; cast plaster on burlap ; cast stone on burlap ; Zono- 
lite plaster on burlap covered chicken wire (two thicknesses) . These 
ten tests, curves for which have been published in a preliminary re- 
port, will be supplemented by four others, the material to be selected 
after consideration of results of the present tests by the studios. 
The subcommittee proposes to continue its work by studying 
(1) the question of the open ceiling, making reverberation measure- 
ments in the studios themselves; (2) the placement of microphones 
with reference to the focal length of the camera lens; (3) the effect 
on the absorption-frequency curve of bracing the sets by various 
spacings of the braces in back of the set material. For the measure- 
ments made to date, the material has been rigidly braced for the 
prevention of resonance. 

I V-D Release Print Quality. Another subcommittee, with Frederick 
M. Sammis as chairman, has been studying the question of the pro- 
duction of high-quality release prints. The producing industry 
has heretofore been rather lax as to laying down specifications as 
to release print quality; and it seemed logical, particularly in view 
of the more exacting need for high quality imposed by the coming 
of sound-on-film pictures, that the cooperation between studios, 
laboratories, and exchanges in this matter be strengthened. It 
was the first task of the subcommittee to survey the methods in 
use for the production and inspection of release prints, and to study 
these methods in the light of the quality of prints produced. The 
subcommittee has worked out certain standards for processing and 
inspection, based on the best current practice, and will endeavor 
to secure the general adoption of these standards. In this, the 
cooperation of the exchanges and of the service departments of the 
major electrical companies, is being enlisted. Two releases for edu- 
cational purposes were planned: the first, which is already available, 
containing the characteristic annoying sounds resulting from in- 
efficient projection; the second is to contain disturbing noises re- 



July, 1930] ACTIVITIES OF THE ACADEMY 13 

suiting from improper laboratory procedure or deficiency in handling 
by exchanges. Exchanges will be urged to make it a practice to 
maintain the quality in the laboratory print by proper handling in 
transit, and by periodical cleaning in accordance with accepted 
specifications. 

The final report of the subcommittee will suggest standards of 
high-quality release print production, including: transit and storage 
of the negative; construction of laboratory buildings; dustproofing 
precautions; cleaning of the negative; printing equipment, mainte- 
nance, and care thereof; development equipment, and its use and 
care; assembly ;- visual and aural inspection of prints; and, as men- 
tioned above, treatment of prints by exchanges. 

IV-E Release Print Standards. As there are at present no stand- 
ards for the makeup of release prints, the length and divisions of 
leaders vary with every studio. Exchanges report that theater 
operators are cutting off leaders, substituting leaders of their own, 
marking crude visible signals for changeover, etc., the resulting 
waste of film and mutilation of prints constituting a serious problem. 

This problem was dealt with by an active committee from the 
Academy Technicians' Branch, the Pacific Coast Section of the 
Society of Motion Picture Engineers, Chapter No. 7 of the Ameri- 
can Projection Society, and the American Society of Cinematog- 
raphers. The members of this committee, which has become a 
subcommittee of the Producers-Technicians Committee, are: S. J. 
Twining, Chairman; A. J. Guerin, Sidney Burton, N. H. Brower, 
I. James Wilkinson, Gerald F. Rackett, and Donald Gledhill, Secretary. 

The group prepared a set of tentative specifications for a standard 
release print, embodied them in a detailed blueprint, and made up 
two sample reels to demonstrate them. The subcommittee then 
met with the appointed representatives of fourteen studios, who 
considered these specifications favorably, except for a few minor 
points which will be settled shortly. The revised standards will 
then be published by the committee. 

IV-F Screen Illumination. Prior to the organization of the Pro- 
ducers-Technicians Committee, there already existed a joint com- 
mittee of the Pacific Coast Section of the S. M. P. E-, the Academy 
Technicians' Branch, the American Society of Cinematographers, 
and Chapter No. 7 of the American Projection Society, appointed 



14 IRVING THALBERG [J. S. M. P. K. 

to deal with the subject of standards for screen illumination. The 
members of the committee were: Emery Huse, Chairman; John 
O. Aalberg, J. A. Ball, Dr. John T. Frayne, Russell H. McCullough, 
Peter Mole, John M. Nickolaus, Gerald F. Rackett, Richard Towers, 
and Sidney J. Twining. This body has continued its work under 
the auspices of the Producers-Technicians Committee. 

Minimum standards will be formulated for illumination attainable 
by the majority of theaters. Because of economic considerations, de 
luxe houses will exceed these and very small houses will not be able to 
reach them, but they will be practicable for the great majority of houses. 
The density of release prints can then be related to this standard. 

For preliminary investigation the committee selected six repre- 
sentative local theaters. In each of these the committee measured 
the illumination produced at the screen, without any film in the 
projector. It was found, however, that the same print, shown in 
two theaters in which the length of throw and screen illumination 
measurements are approximately equal, may look very different. 
This fact led the committee to further inquiry into the type of light 
used in the projector. There appeared to be some evidence, for 
instance, that mirror lamps and high intensity lamps which reflect 
equal foot candles from the screen when projected through a clear 
film gate, differ in how much light they put through film. The 
problem of the quality of the projected picture seems to center on 
brightness contrast. 

In order to simulate actual conditions in future illuminometer mea- 
surements, test reels have been made up by Emery Huse, chairman 
of the group. The first of these consists of four sections in each of 
which the density is constant (10, 50, 75, and 100 per cent transmis- 
sion). The second will have four density areas appearing on each 
frame. Thus, for the first time a scientific method will be available 
for taking into account the various factors which affect the trans- 
mission of pictorial quality to the screen. 

V. GENERAL FUNCTIONS 

The committee plans, after the present series of investigations 
have been concluded, to attack other important non-competitive 
problems. A number of these are now under consideration. 

At the beginning of 1930, the Technical Bureau, formerly under 
the Association of Motion Picture Producers, was transferred to the 
jurisdiction of the Academy, and thus of the Producers-Technicians 



July, 1930] ACTIVITIES OF THE ACADEMY 15 

Committee. No attempt has been made to differentiate between 
the Bureau's activities and the other technical functions of the com- 
mittee. The Bureau is acting as a place of record and a clearing- 
house for technical information. As a place of record, its function 
is to supply the studios with pertinent information on technical 
problems with which they find themselves confronted. In connec- 
tion with this function, it has on hand a large library of motion pic- 
ture books and periodicals, which is being maintained and expanded. 
As a clearing-house, the Bureau is serving to keep the individual 
studios abreast. of current progress in all technical developments, 
particularly the investigations conducted by the subcommittees. 
In addition to publishing progress reports, the committee also 
circulates the Academy Technical Digest. The Digest, which was 
begun in connection with the Academy's Sound School mentioned 
above, consists of a series of fundamental, yet up-to-date, reviews 
of the technical knowledge in various fields. Through it, papers 
of scientific and educational nature, as well as records of individual 
achievements among the various studios, are distributed directly 
to the industry. 

To take care of several problems of mutual interest, such as 
that of standardization of camera and projector apertures, as de- 
scribed by the committee's secretary, Lester Cowan, in the January, 
1930, number of the JOURNAL; that of standardization of release 
print leader and changeover cue; and that of screen illumination, 
the committee has established a degree of contact with exchanges 
and theaters. It is planned to maintain this contact in so far as it 
will improve the correlation of theater and studio practices along 
technical lines. 

Finally, the committee is commencing cooperative contacts with 
the laboratories, factories, and local representatives of equipment 
manufacturers, and with your Society. The expansion of this ac- 
tivity will serve excellently in interpreting the needs of the producing 
industry to the manufacturers, and in acquainting the studios with 
manufacturing developments. The Academy therefore looks for- 
ward eagerly to the growth of such cooperation. 

DISCUSSION 

MR. Ross: I should like to ask whether a single rectifier is used with each 
arc lamp. 

MR. TOWNSEND: In most cases the checks are put at the bottom of the arc. 
MR. Ross: An automatic inductance of known form could be placed in series 



16 IRVING THAI,BERG 

with the generator at the generating plant. The electrolytic condenser could 
also be made automatic and the movable element thereof connected to the 
moving arm of the automatic inductance in a manner to automatically change 
the capacity of the* circuit simultaneously with changing the impedance thereof. 
This would remove the inductances and condensers from the studios. 

MR. TOWNSEND : That was used originally and given up in favor of the method 
shown. 

MR. TAYLOR: To what extent does the running of this sound school resemble 
that of a college or university? 

MR. TOWNSEND: During the operation of the sound school the members were 
chosen by the studios. The initiation fee was $10 including tuition to all the 
lectures and printed matter obtained from them. In some cases the motion 
picture companies took it on themselves to pay the entrance fees. The men in 
attendance were from all branches of the industry. Some of the most interested 
were from the ranks of the directors. The apparatus required for the investiga- 
tion of the problems was supplied, some from the studios, but a large portion 
was supplied by Electrical Research Products, Inc. They turned over their 
laboratories to the Academy and, where they were too limited, we worked at 
the University of California. In this school, for the first time, people from the 
competitive laboratories met and discussed their problems. It seems strange 
to find the competitive spirit as strong here as it is after having lived in that 
atmosphere out there. 

PRESIDENT CRABTREE: Those of us who visited Hollywood two years ago 
have a clear picture of the Academy. It is very important that there should be 
the closest cooperation between our Society and the Academy, especially with 
regard to standardization. Our Standards Committee is studying screen illumi- 
nation and wide film dimensions as well as nomenclature. The Academy has 
similar committees, and it would be ridiculous for the Academy to put out one 
list of nomenclature and our Society another. I have appointed on various 
committees a member of the Academy, and I should like to see more collabora- 
tion, but the world was not made in a day. One of the reasons for the success 
of the Academy is the fact that it has a number of paid employees. If it had 
to depend on voluntary help, as the Society of Motion Picture Engineers has to, 
I am afraid it would not have been able to do the fine things it has done. 
I think the Academy has set a fine example for us to follow in establishing 
courses of education. I hope that our Society can get something going along 
these lines. The best form which this should take has not crystallized in my 
mind, but I think we should contribute to the industry by assisting in the 
education of the engineer. 

I wish Mr. Townsend to convey to the Academy our thanks for the papers 
they have sent along, and we send our greetings and best wishes, and the Board 
is already considering the matter of putting Hollywood on the ballot for the 
convention next spring. Personally, I am pushing very hard for a spring con- 
vention in Hollywood. 

MR. TOWNSEND: I was asked by the Academy to urge you to hold the next 
convention out there. 

PRESIDENT CRABTREE: It is a little too warm there in the fall so we will 
consider very carefully coming next spring. 



TALKING PICTURES THE GREAT INTERNATIONALIST 
HAROLD B. FRANKLIN* 

The history of the motion picture business is a history of unex- 
pected accomplishment and unrealized opportunity. Its success 
has ever been greater than anyone expected it would be; its in- 
fluence has gone far beyond the wildest hope of even its most en- 
thusiastic visionaries. Its success, in short, has been too good to 
be true. 

No one who looked at Fulton's first steamboat dreamed of the 
North German Lloyd liner, Bremen. Anyone who, after seeing 
the Wright Brothers when they first flew at Kitty Hawk, would 
have been wild enough to presage Lindbergh's trip to Paris, would 
have been put in an asylum. 

This modesty of vision has, after all, been true in respect to all 
great inventions. And the point is, I suppose, merely that the 
motion picture is no exception. 

Like the chorus girl who turned down the gift of a book because 
"she had a book," there was the film man who came to Seattle in 
the early 1900's to open a film exchange, but refused to open one 
when he found there already was a film exchange in that city. 

Mitchell Mark, running the famous pioneer Strand Theater in 
New York City, was very much upset and worried when another 
picture theater was going to open on Broadway. Marcus Loew, 
bless his soul, appealed to his friend Zukor not to go ahead with the 
Rialto Theater because it would put too many seats on Broadway! 

Always this lusty youngster cub of an industry has been far, far 
ahead of the imaginations of its founders and its operators. The 
most eloquent medium ever discovered for the presentation and ex- 
change of ideas, its precocity has ever been retarded because its 
eventual accomplishments seemed unbelievable miracles until they 
actually happened. 

The reason for this is that nothing ever existed like it before; 

* Fox West Coast Theaters, Los Angeles, California. (Read before the Society 
at Washington.) 

17 



18 HAROLD B. FRANKLIN [J. S. M. P. E. 

no such power for world-wide education and propaganda. Naturally 
then, no one could ever dream how far and wide its influence would 
eventually become. 

For years, the silent picture was working a leaven of world-wide 
propaganda, unnoticed. The internationalism of this influence, 
though tremendous, was never taken advantage of, not even realized, 
until long after its results were so obvious as to be daily memoranda. 

Take a news weekly shot of Japanese people in bathing, and what 
do we find? American one-piece bathing suits. What country 
is there in the entire world unacquainted with the American Cow- 
boy and the American Indian? Every corner of the globe has learned 
what Lindbergh looks like. 

Perhaps internationalism is too strong a word for all this. An 
internationalization of appreciation fits it better. The exchange of 
pictures between countries has for years been acquainting each coun- 
try with its neighbor's peoples, habits, and clothing, as nothing be- 
fore in history ever did. To some extent, merchants did finally wake 
up long after the influence was first felt, to this fact: that trade 
was no longer following the flag but was following the shadowy 
legends 6f the screen instead. 

But now we enter a more definite phase. A more acute and a 
more telling influence is on the way, because talking pictures are 
here. And this new influence will also go unrealized, and unsung, 
until long after it starts its miracles. 

A talking picture intensifies whatever a silent screen would do. 
When characters speak from the screen, they become more inti- 
mate, more real; speech intensifies Life. No matter how effective 
your silent sequences might have been, they still were shadows, 
legends, phantoms. Once they become vocal, however, they be- 
come people; they come right off the screen into the laps of the 
audiences and whatever their effect was while mute, it trebles, 
and trebles again, in voice. 

There is a belief among all of us that no matter what our differences 
may be with other people, if we could but sit down and talk with 
them we could wipe those differences away. We believe this be- 
cause we know that without a heart to heart exchange of soul, and 
search of mind, we can never see the other fellow as he actually is, 
nor can he see us. All of us thought, throughout the Great War, 
that if we could have but joined our enemy in intimate talk we would 
no longer be enemies. Speech may have been invented to hide 



July, 1930] TALKING PICTURES 19 

thought, yet no matter how imperfect, there is no understanding 
without it. 

Such a medium for understanding is the talking picture. Peoples 
of the world will speak to each other for the first time in the whole 
history of the world. Hopes, customs, traditions, ideals, will be 
exchanged. Familiarity, sympathy, will come from them. Talk- 
ing pictures will have the same effect as if nations visited in the 
homes of other nations. The homely little things that make us 
human, the breakfast table, the family life, will give each country 
a chance to see that its neighbor and its enemy are human exactly 
like itself. The world will receive and maintain an intimacy within 
itself that has been available hitherto to no entity larger than a 
village, and the talking picture will do it. 

True, this is a long way off ; much will have to happen first. Trade 
embargoes will have to be lowered; languages will have to, and will 
be, altered, unified. It may be centuries, but the United States of 
the World is going to come, and when the history of its vivid arrival 
is written, a talking picture will have, it seems to me, the star role. 

If I may be permitted to prognosticate, I think the first step will 
be a unification by languages. All countries that speak Spanish, 
for instance, will see the same kind of Spanish motion picture; all 
countries that speak English, will see the same kind of English mo- 
tion picture; and so on, throughout all the major languages we 
have. Long after this unification by languages is accepted, there 
will begin a gradual breaking down of even those few divisions which 
will remain due to the language barrier. Then, with the final break- 
ing down of that barrier there will arrive a unification of the world 
on such a vast and happy scale that the mere prophecy of its com- 
ing is enough to stamp me as a wild visionary. 

What that language will be, and which civilization will so domi- 
nate the world as to dictate its syllables, no man can say. There 
is no doubt in my own mind that its course of accomplishment will 
be such as to reiterate the age-old theory of the survival of the fittest. 

But people are so curious, so gregarious, so ambitious, and, I am 
sorry to say, so greedy, that these fundamental human traits will 
seek and demand what talking pictures will teach them is feasible 
a world-wide presentation of the best in everything, a universal 
understanding, and a cosmic peace. 



THE REVOLVING LENS WHEEL PROJECTOR 

ARTHUR J. HOLMAN* 

The desire to reproduce motion in pictures, for the purpose of 
study and analysis, is the origin of the great motion picture industry. 
The stroboscope, as you know, was one of the early and rather crude 
instruments developed for motion study, and, strange as it may 
seem, its basic principles are still employed universally wherever 
motion pictures are shown. I refer particularly to the picking out 
of portions of a complete action by the shutter mechanism of the 
motion picture camera, and the presentation, through the medium 
of an intermittent mechanism, of these same portions of action on 
the screen of the theater. Such a recording and reproducing system, 
involving intermittent film movement, must necessarily fall far 
short of the ideal for the following reasons: 

First, the screen illumination is entirely unnatural in that it pul- 
sates rapidly from zero to maximum value. 

Second, the maximum light intensity on the screen must be ex- 
cessive to secure the desired average brightness because of the shutter 
cut-off. 

Third, rapid actions have a jerky appearance, for even persistence 
of vision, that physiological and fundamental foundation of present- 
day movies, cannot fill in the action obliterated by the camera shutter. 

To eliminate the stroboscopic principles from motion picture 
presentations and to remove, or at least mitigate, the evils of inter- 
mittent illumination, have been the goal and aim of inventors and 
experimenters for many years, and more ideas have been conceived 
to this end than most of us are aware of. As is usually the case, 
however, the most fantastic and utterly impossible optical systems 
and mechanisms have been promulgated by both novices and those 
skilled in the art, and the simplest and most logical means has been 
meticulously avoided, the only apparent reason being that the sim- 
ple system is considered utterly impossible by those well grounded 

*59 Auburn St., Brookline, Mass. (Read before the Society at Washington.) 
20 



REVOLVING LENS WHEEL PROJECTOR 21 

in optical theory. But the "impossible" is often the most fruit- 
ful ground for research and invention, and the more certain the 
authorities are that "it can't be done," the more likely are the pros- 
pects for discovery. It has ever been thus. 

In the language of the Patent Office, this invention relates to 
that type of projecting apparatus, or camera, wherein the film strip 
is kept continuously in motion and the effect of said motion is so 
compensated by means of moving optical rectifying elements as to 
produce a well-defined image. A complete mental picture of our 
ideal projector may be gained from the following: 

Let us suppose that we have an aperture across which a film strip 
may be actuated, a light source, and condenser system which will 
illuminate uniformly the area of this aperture, and an objective 
system which will distribute light passing through the aperture in 
such a manner as to produce a uniform illumination over the entire 
area of a screen. Now suppose that a film strip is moved across 
the aperture at a uniform linear velocity, and the objective system 
is so constituted that it will form on the screen a stationary image 
of each film frame, and will accomplish the transition from frame 
to frame, as the film advances, through the medium of a dissolving 
action, without varying the light intensity or interfering with the 
definition of the resultant screen image. In other words, we wish 
to provide an optical system capable of producing uniform maximum 
illumination over the entire surface of a screen, and having the ca- 
pacity to modify the intensity locally in proportion to the density 
of the corresponding part of the film frames which are passing con- 
tinuously over the aperture plate. Measured against such an ideal, 
the present system of intermittent projection shows up as a poor 
makeshift. ^ 

Much thought has been devoted to solving the problems arising 
as men have sought to eliminate the intermittent movement and 
approach more closely to the recognized ideal. Many, many sys- 
tems have been thought out and tried, and a few very ingenious 
devices have been constructed, but they have all fallen by the way- 
side due to inherent mechanical or optical difficulties which make 
them impractical. Reflecting systems have been used almost ex- 
clusively by searchers after the ideal, and one or two of these have 
been developed to a high state of perfection, but they fail in service 
because they involve complicated mechanical movements which 
require cams for their accomplishment; moreover, reflecting sur- 



22 ARTHUR J. HOLMAN [J. S. M. P. E. 

faces of great optical accuracy are not easy to manufacture or main- 
tain at high efficiency in service. Although spectacle makers have 
long recognized and used the prismatic power of decentered thin 
lenses, it has occurred to very few that this principle might offer 
the easiest approach to the perfect system of recording and repro- 
ducing motion in pictures. 

The continuous projector we have developed, and which I will 
now proceed to describe and demonstrate to you, functions entirely 
and solely because of this inherent characteristic of a thin lens which 
produces a prismatic or bending action proportional to the decen- 
tration. It was discovered nearly thirty years ago that an optical 
system comprising a stationary lens element and a pair of overlapping 
revolving lens wheels would produce on a screen a stationary image 
of pictures on a film strip provided the film strip was continuously 
moved across the optical axis at a rate properly proportioned to the 
angular velocity of the revolving lens wheels. Unfortunately, the 
original inventor, lacking one or more of the three essentials, ability, 
financial means, or stick-to-it-iveness, not only never solved the 
problem himself, but left a monument in the Patent Records which 
has been effective in causing investigators to shun the basic idea 
long after the expiration of his patent. Our projector embodies 
the results of a mathematical analysis of the revolving lens wheel 
system and includes many new and original mechanical and optical 
features which are essential to the practical application of this system. 

As stated previously, our ideal projector consists essentially of a 
suitable light source, a condenser system, and an objective system, 
the latter comprising spherical lenses only. The objective system 
is composed of a stationary front element, comparable to the front 
element of an ordinary projection lens, and pairs of rear elements 
which constitute the peripheries of the two revolving lens wheels, 
these pairs of rear elements replacing the rear element of an ordi- 
nary projection lens. The first important feature to be noted is 
that our objective interposes the same amount of glass between the 
aperture plate and the screen as does the ordinary projection lens, 
therefore, its light-transmitting efficiency, with equal lens apertures, 
should be about the same. Moreover, since the axial spacing and 
refractive powers of the elements are comparable to those of an 
ordinary projection lens, there is nothing freakish in the system re- 
quiring special optical treatment. The problem, as far as the objec- 
tive is concerned, is, therefore, reduced to a mathematical analysis 



July, 1930] 



REVOLVING LENS WHEEL PROJECTOR 



23 



which will supply the data required for a proper design of the lens 
wheels and the stationary front element. 

The perfect system would consist of a stationary front element 
and a continuous procession of identical rear elements, all equally 
spaced and moving downward at a constant linear velocity over a 
straight path at right angles to the axis of the stationary element. 
But such an optical rectifying system lies in the realms beyond the 
range of our mechanical ability; therefore, we must substitute for 
the perfect, some mechanical arrangement which is practical and 
which may be so designed as to approach as closely to perfection as 
we may desire. Since rotation at uniform angular velocity is a 
movement well within our mechanical ability to produce, and since 






;-x 



3em& ' = 




FIG. 1. Diagram of objective system, showing position of lens sectors at 
the instant when two film frames are each supplying equal illumination to 
the screen. 

this movement alone is sufficient for our requirements, we have 
chosen, in the present machine, to use a pair of overlapping revolving 
lens wheels. Two lens wheels are used to secure the balancing effect 
of one wheel upon the other, which eliminates all lateral variations 
and thus permits a very close approach to the theoretically perfect, 
with wheels of relatively small diameter. 

In Fig. 1 is illustrated that position of the lens wheel elements 
and the film frames which provides the conditions easiest to analyze 
mathematically. It is to be noted that the edge of a lens sector is 
on the axis of the stationary element, and, if the screen image is in 
frame, the line between film frames will also lie on the axis. Trac- 
ing the ray, parallel to the axis, which passes through the center of 



24 ARTHUR J. HOLMAN [J. S. M. P. E. 

the film frame at the height, x, above the axis, through the elements 
of the objective to the center of the screen, provides the basic equa- 
tions for an elementary mathematical analysis. When these equa- 
tions are solved for values of C, D, and/, with the aid of known mathe- 
matical relations, the three general equations of the decentered 
objective system are obtained. These general equations furnish 
the means for studying the system and predicting the performance 
characteristics of new designs. They are the tools which the de- 
signer may use with assurance. They enable him to know the re- 
sults without constructing the system, and thus put his work on a 
scientific basis. Omitting the derivation, I will give the final equa- 
tions: 



z 



- (2) 

Z 



(3) 



wherein (see Fig. 1), 
C is the axial distance from the optical center of the stationary 

element to the vertical plane midway between co-acting 

lens sectors. 
D is the axial distance from the film strip to the vertical plane 

midway between co-acting lens sectors. 
/ is the focal length of the objective system. 
di is the axial distance from the screen to the equivalent center 

of the objective system. 

/i is the focal length of a pair of co-acting lens sectors. 
/2 is the focal length of the stationary element. 
x is the distance from the center of a film frame to the axis. 

(In Fig. 1 it is equal to one-half the distance between cen- 
ters of adjacent film frames.) 
z is the distance from the optical center of a lens sector to the 

horizontal plane through the axis of the stationary element. 

(In Fig. 1, it is equal to the distance from the optical center 

to the radial edge of a lens sector.) 



July, 1930] 



REVOLVING LENS WHEEL PROJECTOR 



25 



Although these simple equations are not exact, due to the elimi- 
nation of very small complex terms during the analysis, they give 
values of C, D, and /, which are correct within one-quarter of one 
per cent. 

Variation in film shrinkage has always been a serious problem to 
the designer of continuous projectors, but with the above equations 
one can easily figure out the proportionality of the adjustments 
required in the values of C and D. Our machine is equipped with 
a hand adjustment which automatically maintains the correct ratio 
of C to D by moving the aperture plate and front element of the ob- 
jective along the axis simultaneously, thus easily accommodating 
the optical system to any variations in film shrinkage. 




FIG. 2. Diagram showing extremity of active zone of a lens sector. 

The factor, z, which appears in each of the general equations, 
requires further study, for therein is contained the measure of just 
how closely the revolving lens wheel system may be made to ap- 
proach the accuracy of the perfect system. In Fig. 2 is shown a 
lens wheel sector with its radial edge tangent to the circle represent- 
ing the cross-section of the condenser beam at the vertical plane 
midway between co-acting lens sectors. L is the center of the lens 
wheel; is the optical center of the lens sector; R is the radius 
of the circle whereon the optical centers of the lens wheel sectors 
are positioned; </> is the angle formed at the center of the lens wheel 
between a radius through the optical center of a lens sector and a 



26 ARTHUR J. HOLMAN [J. S. M. P. E. 

radius through the axis of the stationary element; d is the diameter 
of the circular cross-section of the condenser beam ; N is the number 
of lens sectors per wheel. In the position shown in Fig. 2, the lens 
sector is just about to enter the light beam, and, from this instant 
until it has passed entirely through the beam to a position in which 
the upper radial edge is tangent to the lower portion of the circle, 
the lens sector is in the active zone. The maximum values of <j> 
and z, which occur at the extremes of the active zone, are designated 
as < max . and z maXt . 

As previously stated, the use of two lens wheels eliminates all 
lateral variations, therefore we are concerned only with variations 
in the vertical component of the downward movement of the opti- 
cal center of the lens sector. Since z = R sin<j>, it is evident that 
z cannot vary directly as </> unless R = infinity, or <f> = 0. How- 
ever, if max . is kept within certain limits, the variation in : - , 

<t> 

over the active range of a lens sector, will be negligible, and within 
these limits there is a wide choice in lens wheel diameter and in the 

number of sectors per wheel. But the variation in - - , from 



</>max. to = 0, measures the nearness of approach to the ideal, 
and governs the residual periodic variations; therefore, it has re- 
ceived prolonged and careful study and its effects have been analyzed 
minutely. It was at one time considered a serious factor because 
of its apparent relation to the focal length of the objective system, 
as shown in general equation (3), but its influence in this respect 
has been entirely overcome by improvements in the design of the 
stationary element, the curvatures of the components of which are 
extremely important in this connection. 

The only residual error in the objective system caused by variation 

in -- , is that represented by a periodic rise and fall of the entire 

</> 

screen image which takes place during each picture cycle. In the 
present machine, this error causes a total vertical movement of ap- 
proximately one-eighth inch in a picture twelve feet wide, and is 
invisible because it takes place twenty-four times per second at nor- 
mal projection speed. The method of calculating this error, which 
I worked out originally in January, 1923, is very interesting but 
somewhat lengthy, so I will not include it in this paper. It will 



July, 1930] 



REVOLVING LENS WHEEL PROJECTOR 



27 



be sufficient to state that this error is inversely proportional to the 
square of the number of lens sectors per wheel, and, with a sixteen- 
sector lens wheel, the maximum departure of the equivalent center 
of the complete objective system from its theoretically correct po- 
sition amounts to 0.000,920,99 inch. This factor, multiplied by 
the magnification ratio, gives the total vertical displacement of the 

, . sin<t> 
screen image caused by the variation in . 



In order that the objective system may function properly, it is 
necessary to provide a condenser system which will illuminate the 
entire aperture uniformly, and will produce a beam having a circular 
cross-section of small diameter at the plane midway between co- 
acting lens sectors. In the interest of economy, it is also essential 



15. 
10. 

5. 

0. 



\ 



\ 



20. 



Q. 1Z. /6. 

OF LENS SECTORS pen WHEEL. 

FIG. 3. Curve showing the relation between the number of lens sectors 
per wheel and the maximum departure of the equivalent center of the 
objective system from its theoretically correct position. 

that the cross-section of the condenser beam, in the plane of the gate, 
be of such shape and proportions that the maximum amount of light 
may be transmitted through the elongated aperture. To accomplish 
these ends, I have long been using a cylindrical surface in the main 
condenser and a complementary sphero-cylindrical gate lens which is 
mounted in close proximity to the film strip. The first-mentioned 
cylindrical element provides a vertically elongated spot at the gate, 
having the form of an ellipse and fitting closely to the contour of the 
elongated aperture. The sphero-cylindrical gate lens remolds the 
condenser beam so that it becomes circular in cross-section as it 
enters the objective system. The projector is now equipped with a 
low intensity reflector lamp having a standard reflector and a con- 



28 



ARTHUR J. HOLMAN 



[J. S. M. p. K. 



denser which was standard before I reground and polished the flat 
surface to cylindrical form. 

Having designed an objective system approaching the ideal in 
accuracy, and having provided a condenser system fulfilling all the 
requirements, the mechanical problems involved in operating the 
lens wheels and film strip in proper relation, remain to be solved. 




FIG. 4. Rear-right side view of complete projector. 

As a first consideration, the mechanism must be easily adjustable 
to meet the requirements of the optical system in regard to film 
shrinkage, and a framing adjustment must be provided. More- 
over, the lens wheels must operate in exact synchronism and the 
film strip must be actuated across the aperture plate at a uniform 



July, 1930] REVOLVING LENS WHEEL PROJECTOR 29 



velocity exactly proportional to the angular velocity of the lens 
wheels. The steadiness, definition, and pleasing qualities of the 
projected image depend almost entirely on the accuracy with which 
these functions are performed. 

Unsteadiness in the projected image has been my most serious 
problem in connection with this work, and since it has been elimi- 




FIG. 5. Right side view of complete projector. 

nated by the installation of precise gears, it is not difficult to show 
that the trouble has been mechanical rather than optical. A better 
understanding of the nature and cause of unsteadiness in the pro- 
jected image may be had from the following analogy: 

Let us think for the moment of the screen image as being sup- 



30 



ARTHUR J. HOLMAN 



[J. S. M. P. E. 



ported in a state of equilibrium by three elastic ribbons, one being 
attached at each of the top corners and the third being attached 
at the middle of the bottom edge. We must think of the image as 
being rigid but having no weight, and moving as a whole if any 
change occurs in the tension of the supporting elastic ribbons. The 
tension of each of the top elastic ribbons, in our analogy, is to be 




FIG. 6. Rear-left side view of complete projector. 

likened to the angular velocity of one of the lens wheels, and the 
tension in the bottom elastic ribbon compares with the velocity 
of the film strip across the aperture plate. Any change in the ten- 
sion of one or more of our imaginary elastic ribbons, unless accom- 
panied by a proportional simultaneous change in all three, will cause 



July, 1930] 



REVOLVING LENS WHEEL PROJECTOR 



31 



a displacement of our imaginary rigid image. In like manner, our 
real projected image is in suspension, and any change in the angular 
velocity of a lens wheel, or in the linear velocity of the film strip, 
unless accompanied by a proportional simultaneous change in ve- 
locity of all three elements, will produce a displacement of our real 
projected image. 

Inasmuch as perfect things are seldom if ever made, and never 
can be made in quantities, and since no means, other than gears, 
are available by which the lens wheels and film strip may be actuated, 




FIG. 7. 



Rear-right side view of mechanism with door and cover plates 
removed. 



it is evident that the more simple the gear train the less difficult 
will be the commercial production of the mechanisms. The present 
model, designed in 1926, can be considerably simplified in this respect, 
and some idea of the improvement may be gained from the follow- 
ing comparison. 

This model has two worms and two worm-wheels between the lens 
wheel shafts; the new model will have but two gears between these 
shafts; therefore the probability of errors in synchronization of the 



32 ARTHUR J. HODMAN [J. S. M. P. E. 

lens wheels, with gears of equal accuracy, is one-half. This model 
has seven gears between each lens wheel shaft and the aperture 
film sprocket; the new design, providing the same flexibility for 
framing and adjustment of the optical system, requires but two 
gears between the aperture sprocket and a lens wheel shaft. It 
is evident, therefore, that the new gear train, with gears having an 
accuracy of the order of those in this machine, will have at least a 
five-to-one advantage over the present arrangement, in the matter 
of steadiness. Moreover, the new gear train is far less expensive 
to manufacture. 




FIG. 8. Right side view of mechanism with door and cover plates 
removed, showing gate open for threading. 

I have purposely avoided any reference to the accuracy required 
in the construction of the lens wheels, as that subject is fully covered 
in an article which appeared in the June issue of the JOURNAL 
(p. 623). It will be sufficient for the present to state that the manu- 
facture of lens wheels, by the usual methods of lens manufacture, would 
be difficult, costly, and generally unsatisfactory. To meet the new 
requirement for quantity production of first quality and exactly 



July, 1930] 



REVOLVING LENS WHEEL PROJECTOR 



33 



matched lenses, an entirely new method of grinding and polishing 
has been developed. A special optical instrument has also been 
devised for exactly positioning the lens sectors on the lens wheels. 
With this new equipment it is not difficult to obtain the desired 
accuracy in the lens wheels and they can be produced commercially 
at a surprisingly low cost. 

Thus far, I have described only the essential features of the re- 
volving lens wheel projector. The fact that the film strip moves 
across the aperture at a uniform rate has many advantages, and one 




FIG. 9. Front-left side view of mechanism with cover plates removed, 
showing lens wheels, brake wheels, balanced drag mechanism, and mount 
for front element of objective. 



of these is the ability to actuate a sprocket, located just above the 
aperture, by the movement of the film strip. This film actuated 
sprocket operates an automatic fire-shutter control mechanism. 
With the fire shutter thus controlled by the movement of the film 
strip across the aperture plate, its response is sure and instantaneous 
in case of film breakage at the aperture, or slowing down of pro- 
jection below the predetermined minimum rate. The projectionist 



34 ARTHUR J. HOLMAN [J. S. M. p. B. 

has no control over the action of this fire shutter, nor does he need 
it, since the shutter cannot close unless there is imminent danger 
of igniting the film. Another advantage of a continuously moving 
film strip is that the tension shoes can function perfectly with very 
little pressure, because there is no effect equivalent to the "over 
shooting," which produces unsteadiness in intermittent projection 
unless the spring tension is considerable. Since there is no periodic 
"breaking from rest" under heavy tension, there is very little strain 
on the film strip in continuous projection, and "green" prints, direct 




FIG. 10. Left side view of mechanism with cover plates removed, 
showing lens wheel shaft assembly and bearings. 

from laboratory processing, may be run without waxing or other 
lubrication. In fact, prints may be projected hundreds of times 
without showing any appreciable wear and without accumulating 
scratches and dirt over the photographic areas. This is an impor- 
tant advantage, especially in the projection of sound-on-film prints. 
Having removed from the projector mechanism the principal 
causes and sources of wear and damage to the film strip, effort was 
next directed toward improving the film take-up device with a view 
to eliminating damage to film from this source. It is pretty generally 



July, 1930] REVOLVING LENS WHEEL PROJECTOR 35 

known that much damage may be done to film during the rewinding 
operation, and the reason is apparent from an examination of the 
wound film when the take-up reel is removed from the lower 
magazine. 

The ordinary take-up drive is a constant torque affair and is ad- 
justed so that the initial winding on the take-up reel will not be 
sufficiently tight to cause damage to the film perforations on the 
lower or "hold back" sprocket. With this adjustment of the driving 
torque, the tension on the film strip, during the initial take-up when 
the wound diameter is small, will be considerably more than is neces- 
sary to produce a solidly wound mass, but, as the diameter of the 
wound mass increases, the film tension decreases, and, generally 
speaking, the outer layers of film, to a depth of one to three inches 
depending on the torque adjustment, are wound rather loosely. 
When the reel containing the film, which has been wound at a pro- 
gressively decreasing tension, is put on the rewinder and the end 
of the film is attached to the empty reel and the motor is started 
with a jerk, it is not difficult to understand that film will be drawn 
from the reel before the reel begins to rotate, and there will be a 
progressively decreasing amount of slippage between film layers, 
from the outer layer down to that inner layer which has been wound 
at a sufficient tension to balance the pull of the power-driven reel 
on the rewinder. If the brake on the reel being rewound has not 
been released, the conditions will be aggravated and the slippage 
between film layers will go deeper into the reel. The film, in pass- 
ing through a projector, collects dust, dirt, bits of emulsion, and 
other grit, which adhere to its surfaces, and when, in the rewinding 
operation, these surfaces slip over each other under pressure, the 
conditions are ideal for the most effective abrading. The film damage 
which shows up as "rain" and is most prevalent toward the end of a 
reel, is generally caused in this manner. 

It is interesting to observe that the advent of sound-on-film prints 
has drawn more attention to the take-up conditions, and the im- 
provement thus far made has taken the form of new type reels with 
larger diameter hubs and of more sturdy construction. These new 
reels, incidentally, cost several times as much as the better grade 
reels of a few years ago. 

Our projector is equipped with a take-up control which may be 
adjusted to give a practically constant winding tension on the film 
for all diameters of the wound mass, and it will operate equally well 



36 ARTHUR J. HOLMAN [J. S. M. p. B. 

with an old-fashioned reel having a two-inch diameter hub, or with 
one of the new type reels. This take-up control is a variable torque 
device, the pressure between the friction drive members being varied 
by centrifugal force through the medium of a system of balanced 
springs. At the higher reel speeds, during the initial take-up when 
the wound mass is of small diameter, centrifugal force acts to reduce 
the driving torque, thus preventing excessive film tension. As 
the reel speed decreases, centrifugal force is reduced and the balanced 
spring system acts to increase the pressure between the friction drive 
members, thereby increasing the driving torque and maintaining 
full tension on the film. Adjustments are provided by means of 
which the film tension may be regulated for three stages of the take- 
up operation, namely, empty reel, half -full reel, and full reel. With 
this device the film is wound on the take-up reel under practically 
constant tension; therefore it acts as a solid mass and is not subject 
to damage during the rewinding operation. 

Continuous projectors which accomplish the transition from frame 
to frame through the medium of a dissolving action without the 
interposition of a shutter effect, must be provided with an aperture 
which is at least two film frames in height; therefore some means 
must be associated with the projector to prevent the appearance 
of images above and below the one centered on the screen. It has 
been common practice to use a mask, placed several feet ahead of 
the projector, for this purpose, but such a device, while effective, 
is nevertheless wasteful as it absorbs images which may be redirected 
to the screen. Our projector, when used with the customary mask, 
is equal in light-transmitting efficiency to the best intermittent pro- 
jector equipped with the best large aperture projection lens. This 
has been proven to the entire satisfaction of representatives of pro- 
jector manufacturers in recent tests. When our projector is used 
in association with an optical economizer having the capacity to re- 
direct the extra images to the surface of the screen in such a manner 
that they may register with each other and with the image already 
on the screen, the light-transmitting efficiency is more than doubled. 

In this connection another very interesting development is made 
possible. In the revolving lens wheel projector, which provides 
a dissolving action occupying a large portion of the picture cycle, 
the aperture is about three frames high; therefore, with the aid of 
an optical economizer, it is perfectly possible to produce on the screen 
a continuous dissolving action involving three separate film frames 



July, 1930] REVOLVING LENS WHEEL PROJECTOR 37 

at all times. This represents the ideal condition for a three-color 
system of natural color projection according to the additive method. 
The individual film frames are not required to carry the full color 
values, as the natural colors are produced on the surface of the screen 
by the mixing of the three primary color values supplied by three 
successive film frames. According to this method of natural color 
projection, the prints are made in black and white, in the usual 
manner, from a negative exposed in a color camera equipped with a 
three-color filter wheel. Filters are necessary to bring out the colors 
in projection, but these will be applied direct to the positive print 
in the form of red, yellow, and blue tints over successive film frames, 
the red tint being applied over those frames printed from the nega- 
tive frames originally exposed through a red filter, etc. This system 
of natural color projection will be relatively inexpensive and will 
have the same resolving power as black and white prints. 

Although the basic idea is that of the old Kinemacolor process, 
it must be understood that the conditions, with a continuous projec- 
tor producing a dissolving action involving three film frames at all 
times, are entirely different from the old Kinemacolor conditions, 
and, therefore, vastly different results are to be expected. The 
question of excessive color fringe due to motion, has been suggested 
as a possible serious fault, but an analysis of the intensity of illumi- 
nation would indicate that color fringing may not be a serious factor. 
When it is remembered that no shutter is used in the projector it is 
evident that the maximum light intensity on the screen is probably 
only slightly in excess of fifty per cent of that required with an inter- 
mittent projector. Moreover, since the screen illumination is being 
supplied from three film frames simultaneously, it is apparent that 
each frame is supplying only its proportion of the total illumination ; 
hence, it would appear that the color fringe, especially on subjects 
not composed entirely of one of the primary colors, would not be 
of sufficient intensity to be objectionable. This system of natural 
color projection has real possibilities, especially in connection with 
sound-on-film subjects, and we expect shortly to be able to demon- 
strate its superiority. 

Continuous projection will be especially helpful in connection with 
the presentation of sound-on-film subjects. This is apparent when 
one recalls that the film strip must move across the aperture plate 
at a uniform linear velocity to satisfy the requirements for steadiness 
in the projected image. Since this is true, there is no necessity for a 



38 ARTHUR J. HOLMAN [J. S. M. p. B. 

sound pick-up attachment to be used with the projector mechanism. 
The sound pick-up can be built into the aperture unit of our projec- 
tor in such a manner as to add no complications to the present ex- 
tremely simple threading arrangement. No extra sprockets or idlers 
are required. Moreover, the film-feeding mechanism may be de- 
signed so that it will successfully handle a film strip having standard 
perforations along one edge only, thus providing room on a 35 mm. 
width strip for the standard silent film frame and a sound track at 
least fifty per cent wider than is now used on 35 mm. film. Thus, 
an opportunity is offered to restore the old silent picture proportions 
and provide an improved sound track without departing from the 
standard 35 mm. width. 

The usefulness of the revolving lens wheel projector is not confined 
to any particular size film frame. A design may be worked out 
for double- width film or for 16 mm. film and such designs will possess 
all the advantages enumerated herein. As a matter of fact the 
system is especially suitable for double-width film because it simplifies 
the optical problems and, due to its two-to-one advantage in light- 
transmitting efficiency, eliminates the difficulties experienced in 
getting sufficient illumination for wide film presentations by the in- 
termittent system. 

The story of the usefulness of the revolving lens wheel is not com- 
plete without a reference to its application to photography. As 
stated in the introduction, the true appearance of motion cannot be 
reproduced from a film depicting only fragments of the original 
movements. Hence, it is logical to believe that action, as recorded 
by a continuous camera having no shutter effect, may be reproduced 
in the most realistic manner by a continuous projector using prints 
from a negative exposed in such a camera. We are now investi- 
gating these possibilities. 

DISCUSSION 

MR. PALMER : I would like to inquire regarding the stability of the lens setting 
under operating conditions, that is when it is subjected to temperature variation, 
vibration, and varying wear. 

MR. HOLMAN : With regard to the stability of the system as affected by wear 
and shock, I can say that this set of lenses was set originally in April, 1927, and 
has not been shifted since. I have taken the projector to New York on two 
occasions in the back of my old Buick and brought it here in the same manner. 
When I tried it out this morning it worked as well as it did in Boston a few days 
ago. Temperature is not a factor because a lot of glass is exposed to the beam 
and therefore the lens wheels do not heat up much. This mechanism was built 



July, 1930] REVOLVING LENS WHEEL PROJECTOR 39 

in 1926 and nothing has been done to the bearings since the machine was com- 
pleted. The wear to date is equivalent to nine months' steady service in the 
theater. 

MR. EDWARDS: I should like to ask what speed the projector operated at in 
this demonstration. 

MR. HOLMAN : The projection was at the rate of about 80 feet a minute. 

MR. DUBRAY: What provision is made for shrinkage accommodation? 

MR. HOLMAN : Film shrinkage is a problem in the design of any continuous 
projector, with which I have dealt at length in the paper. Previous systems 
have had a real tussle with this problem. In mirror and prism systems it is 
difficult to deal with, but in the revolving lens wheel system the solution is simple. 
The lens wheels are not adjustable along the optical axis of the machine. The 
front element is adjustable axially, as is also the aperture unit. These parts 
are slidably supported on pins and the two are moved to compensate for film 
shrinkage. It is a very simple matter to design lever arms having the proper 
ratio to allow for compensation for film shrinkage. The set-up here does not 
differ much from what I have had in Boston. The throw is somewhat longer and 
the pitch angle is greater, but, as regards shrinkage adjustment, there is no 
difficulty; it merely means taking hold of, and turning a hand adjusting wheel. 
The operator really doesn't realize what is happening when adjusting for shrink- 
age; he is changing the position of the front element and the projector aperture 
plate with respect to the lens wheels. This changes the back focus because the 
aperture unit moves away from or toward the revolving lens wheels; however, 
the corresponding movement of the front objective with respect to the revolving 
lens wheels also varies the equivalent focal length of the system simultaneously. 

MR. SHAPIRO: Has Mr. Holman any figures as to the light efficiency of his 
projector as compared with the intermittent type with the same source of light? 

MR. HOLMAN: I am sorry to say I have never measured the light intensity on 
the screen. We ran comparison tests a month or so ago with a Simplex equipped 
with the Ross lens, and the conclusion was reached that there was no difference 
in screen illumination with the two machines under the same conditions; i. e., 
equal arc amperage, lens opening, etc. These tests were made using a mask such 
as I have here today. It is possible, however, to put on the screen the light now 
lost on the two fiber sheets forming the mask, by using an optical economizer, 
and under these conditions the light transmitting power of the system is about 
double that of the ordinary intermittent machine. 

MR. ROBIN : Is the relative speed of the wheels half the angular velocity of 
the film? What means besides the brake has been provided for wear or backlash 
in order that the two optical elements will register in optical centers at the same 
moment on the optical axis? 

MR. HOLMAN: In regard to the speed of the wheels with respect to the film, 
that has puzzled lots of people. There is no definite prescribed relation except 
that one lens sector cross the optical axis in the time required for one film frame 
to cross the axis. The relative velocity in this machine can be figured out. The 
optical diameter on which the lens sector centers are set is 12 inches, and there 
are 16 lenses on the wheel, so you can figure out the ratio of movement of film 
and lenses. There is an opinion abroad that the ratio must be one to one that 
the lens sector must be the same height as the film frame, but this is incorrect. 



40 ARTHUR J. HOLMAN 

In regard to wear, it is to be noted that normal wear in gears and bearings is not 
a serious factor unless it is uneven or excessive in amount, because all parts are 
operating under a uniform and constant load. The sprocket overcomes a uni- 
form film drag and the lens wheels operate against a uniform brake load. 

MR. RICHARDSON: I should like to ask whether we could at some future time 
run sharp black and white film through the machine? 

MR. HOLMAN: We should be glad to, if another showing can be arranged. 
I can assure you that there is no difficulty in securing sharp definition. 

MR. FINN: I should like to know whether any provision is made for precise 
adjustment in film splicing. 

MR. HOLMAN: There is no precise adjustment required in making film splices. 
The sprocket actuating the film across the aperture plate is a standard Simplex 
intermittent sprocket and it is positioned 2 : /4 inches below the optical axis. If 
the splice is good enough to run over the sprocket, there will be no appreciable 
jump in the picture. 

MR. GOLDEN: Is there any additional time required for re-threading in the 
case of breakage? 

MR. HOLMAN: Threading is about the same as in other machines but the 
mechanism is open and large and there is no main shaft in the way, so that there 
is plenty of room. There is the usual top sprocket feeding the top loop, an 
aperture unit sprocket, and the bottom or hold-back sprocket. Most projection- 
ists find our mechanism easier than any other to get into. 



A MICROPHONE BOOM 

ELMER C. RICHARDSON* 

When sound motion pictures were first produced in the Holly- 
wood studios, the sets were small, and no great difficulties were en- 
countered in concealing microphones within the set, so that sound 
could be satisfactorily picked up. 

As the sets became larger it became necessary to use a plurality 
of microphones, and to fade from one circuit to another as the actors 
moved about. This operation of fading from one microphone to 
another contributed to errors in recording which while excusable a 
year ago would be highly criticized today. 

To obviate the use of plural microphones several devices were 
used. For instance, a microphone was sometimes suspended from 
the ceiling by means of a cord and moved about with a long pole, 
an operation quite obviously called "fishing." Some studios had 
their property departments construct supporting arms or booms 
which would facilitate the quick placement of microphones. Most 
of these pieces of equipment were hurriedly made and crudely con- 
structed and none too satisfactory in their operation. 

The Metro-Goldwyn-Mayer Studios, after some experimentation 
with a microphone boom of this type, designed and built a boom 
of the type illustrated in Fig. 1, which operated quite satisfactorily. 
This boom consisted of a substantial base supporting a vertical 
column which in turn supported a lever arm having an adjustable 
portion which could be extended or retracted at will by operating 
a cable drum by means of a crank from the floor. The under- 
balanced portion of the boom and the weight of the microphone 
was counterbalanced by a fixed counterweight and the boom operated 
upon its vertical and transverse axes by an operating lever, as shown 
in the illustration. 

While there are some sound engineers who object to the use of 
moving microphones, many of the best technicians are convinced 

* Mole-Richardson, Inc., Hollywood, California. (Read before the Society 
at Washington.) 

41 



42 



ELMER C. RICHARDSON 



[J. S. M. P. E. 



that the inherent limitations of the microphone can be overcome by 
silently moving the microphone to maintain it in a proper relation 
to the sound source, and by properly manipulating the fader. 




FIG. 1. Microphone boom designed by Metro-Goldwyn-Mayer. 




FIG. 2. Extension tube carrier, Type M-R 103-103A. 

As is true with many of our problems, the general principle in- 
volved in this design is simple; the real problem, however, was to 



July, 1930] 



A MICROPHONE BOOM 



43 



construct this piece of apparatus so it would operate with a degree 
of silence which would in no wise interfere with sound recording. 
In the type illustrated, the sliding tube was operated by two 
leather-faced friction rollers, which were rotated by a cable which 
was wound over a capstan sheave. The whole apparatus worked 
quite silently, but there still remained a slight snapping sound as 
the wires of the cable changed their position on this capstan. To 
overcome this difficulty, another type of extension tube carrier 
was designed. (Illustrated in Fig. 2.) In this case, the extension 
tube rolls in and out of the fixed tube, supported on a leather-faced 




FIG. 3. Microphone boom, Type M-R 103-103A. 



roller having an eccentric adjustment for centering purposes, but 
instead of being moved by friction it is moved by a direct pull from 
a cable attached to the rear portion of the sliding member and op- 
erating in the annular space between the stationary and sliding 
tubes. This cable passes back to a simple sheave supported at the 
fulcrum point of the fixed tube and down to the operating drum. 
It is wound around the operating drum several turns and passes 
around another simple sheave at the fulcrum point, returning through 
a sheave in the rear of the fixed tube, and is rigidly fastened to the 



44 



ELMER C. RICHARDSON 



[J. S. M. P. E. 



sliding member. This construction gives a positive motion to the 
sliding tube with a construction which introduced no serious prob- 
lems of extraneous noise. This type of boom (M-R 103) is illus- 
trated in Fig. 3. 

A number of ingenious suspensions for the microphones have 
been worked out, such as hanging the microphone on rubber suspen- 
sion loops and mounting upon sponge rubber shock absorbing mecha- 
nisms. One of the most successful mountings was worked out in 
the Pathe Studios by suspending the microphone from the center 
of a rubber diaphragm about six inches in diameter. By means 




FIG. 4. Microphone boom, Type M-R 103- A (extended). 

of these various rubber suspensions all "telegraphed" sounds were 
withheld from the pickup circuit. 

Since the microphones have certain directional characteristics 
many of the studios have taken advantage of this and constructed 
suspensions which allow the microphone to be faced at will by the 
operator. In this way, for instance, if a conversation is being carried 
on between two persons, the microphone may be faced from one to 
the other, giving better recording results than would be the case 
if the microphone were held in a constant position. 



July, 1930] A MICROPHONE BOOM 45 

Practically every major studio on the West Coast, and some of 
the studios in New York, have been using these booms with good 
success. 

A demand arose for an automatically counter-balanced micro- 
phone boom which could be operated from the top of a camera 
booth. To meet this situation, the M-R Type 103-A boom was 
developed. The same principles of design for moving the tele- 
scoping portion have been incorporated in this boom as in the Type 
M-R 103, but the counterpoise is mounted on a carriage which 
slides on the rear portion of the fixed tube supported by leather- 
faced rollers and operated by means of a sheave system working on 
the principle of a double block and fall. The counterpoise moves 
outward one foot when the sliding tube and microphone are extended 
three feet. This gives the advantage of always maintaining the 
boom in a state of balance, and by underslinging the boom from 
its fulcrum bearing the boom will always return to a horizontal 
position when it is released. 

This boom is mounted on a tripod which may be elevated (see 
Fig. 4), and has a number of advantages which have been well ac- 
cepted by the studio operating personnel. 

It does not matter whether or not one objects to the use of the 
moving microphones (other technicians are probably more familiar 
with the pros and cons of that subject), the fact remains that micro- 
phones must be placed. In the Hollywood studios, a picture of any 
size is carrying an overhead charge of from ten thousand dollars 
a day up. Every minute gained in the production time is money 
saved. If you have ever observed sound operators trying to place 
microphones by means of rope suspensions, fishing, etc., it is quite 
obvious that a device such as has here been described has a very defi- 
nite place in sound motion picture production. 



TILT HEADS AND ROLLING TRIPODS FOR CAMERA 

BLIMPS 

ELMER C. RICHARDSON* 



Though there has been considerable progress made in silencing 
the movements in motion picture cameras, there are not at present 
available many cameras sufficiently silent, so that they may be 
used without the additional sound-proofing of a camera booth, or 
with what we term a "blimp" or "bungalow" camera housing. 

Sooner or later camera manufacturers are going to offer the in- 
dustry a camera so silent that it can be used with every facility which 
cameras previously used in silent pictures; however, at present 
the sound departments of most studios are resorting to the use of 
blimps as the best means to meet the present situation. 

There has been a lot of experimentation with these sound-proof 
devices. For instance, some blimps have consisted of a simple 
padding or quilted cover attached to the camera by means of snaps 
or zippers. These sound-proofings are popularly called "horse- 
blankets." Other blimps have been constructed of plywood or. 
masonite cases, lined with sponge, rubber, felt, and many other 
insulating materials. 

When the writer left the West Coast, the most popular "blimps" 
were of a construction embodying an aluminum external housing, 
lined with insulating felt and in some cases with lead. I believe 
another paper has been written with respect to these developments. 

At first these blimps were mounted on ordinary camera tripods, 
and in the case of the horse-blankets the addition of the sound- 
proofing, which did not add much weight, did not present a serious 
problem. These heavier "blimps" which are now looked upon 
with favor, weigh approximately 260 pounds with the loaded camera, 
and are too heavy to be supported by either a standard tripod or a 
standard tilt head. 

To meet this situation, there has been introduced a rolling tripod, 

* Mole-Richardson, Inc., Hollywood, California. (Read before the Society 
at Washington.) 
46 



HEADS AND TRIPODS FOR CAMERA BLIMPS 



47 



which in combination with a special tilt head, as shown in Fig. 1, 
gives the cinematographer almost the same latitude with the heavy 
blimp and camera that he formerly had in the days of silent pictures. 
As you will note in the illustration, the tripod is mounted on rubber- 
tired casters, which may be locked into line for "perambulator" 
shots, or left free as desired. At the supporting points leveling 
screws are provided with which the tripod and camera may be lifted 




FIG. 1. Rolling tripod, low position. 

off of the casters and leveled. These leveling screws were given an 
angular inclination which has provided a very rigid support. 

The tilt head is supported upon a central telescoping tube system, 
and by means of a hand- wheel may be elevated or lowered. Fig. 1 
shows the tripod in the low position and Fig. 2 in the high posi- 
tion. Supplementary telescoping struts extend from the base to 



48 



C. RICHARDSON 



[J. S. M. P. E. 



the tilt head, which may be locked by means of clamping sleeves. 

Mounted upon this supporting structure is a tilt head which is 
better illustrated by the detail in Fig. 3. 

As you will note, the blimp is mounted upon a table, which in turn 
rolls upon rails which are sectors of a circle, the radius of which cen- 
ters at a point coinciding approximately with the center of gravity 




FIG. 2. Rolling tripod, high position. 

of the blimp. By this method of support, the blimp and camera 
are in equilibrium in all positions of tilt. 

When free tilt is desired, the knurled clutch knob shown under 
the table is shifted to the right, which disengages the tilt worm re- 
duction gear and spur gear drive to the gear sectors on the table. 
If the blimp and camera are to be operated by the control wheel, 



July, 1930] HEADS AND TRIPODS FOR CAMERA BUMPS 49 




FIG. 3. Detail of tilt head. 




FIG. 4. Auxiliary low tripod. 



50 KLMSR C. RICHARDSON [J. S. M. P. E. 

the clutch is shifted to the left, connecting the worm reduction gear 
to the spur gear driving shaft. 

The panning movement may be mechanically operated by the 
hand wheel on the left, as illustrated in Fig. 3. By withdrawing 
the locking plunger under the support plate, the panning action is 
made free. It will be noted that the hand-wheel controlling the 
passing movement may be moved to the right hand shaft extension, 
if desired. 

By liberal use of ball and roller bearings, friction has been re- 




FIG. 5. High-hat unit showing adjustable section. 

duced to the minimum a very essential feature in handling a camera 
when covering action. 

In addition to the standard tripod, shown in Fig. 1, which supports 
the camera at a lens height of from 70 l / 2 inches high position to 
48 Y inches low position, an additional low tripod may be used 
when it is desired to operate from below 48 inches lens height. (See 
Fig. 4.) The low position of this auxiliary tripod is 37 l /z inches. 
If it is desired to operate at a still lower position, the tilt head may 
be mounted on a sectional high-hat, illustrated in Fig. 5, by ad- 
justing the sections of which the camera may be lowered an inch 
at a time to a lens height of 20 inches from the floor. 



July, 1930] HEADS AND TRIPODS FOR CAMERA BUMPS 



51 



By the use of these several units the camera may be operated at 
any desired height. 

Experience has shown that 90 per cent of production photography 
may be made with the standard tripod. 




FIG. 6. Rolling tripod modified for lighter blimps. 



For use with the type of blimps which are light enough to operate 
from a standard camera base, another type of rolling tripod of modi- 
fied design (see Fig. 6) is available. This piece of equipment has 



52 ELMER C. RICHARDSON 

proved popular in such studios as use these may we call them 
medium weight blimps. 

Every change of production procedure has presented its prob- 
lems. The camera booth was the first solution to the problem of 
silencing camera noise. The blimp has been a modification and its 
use has made necessary the equipment herewith described. 

Until suitable silent cameras are available in quantity to meet 
the needs of the studios, it will probably be that blimps of some 
type will most ably meet the situation. 



VOLUME CONTROL BY THE SQUEEZE TRACK 

WESLEY C. MILLER* 

The proper regulation of volume or apparent loudness is essential 
to good reproduction of sound. This is particularly true when the 
sound forms a part of a sound picture, as the success of the latter 
in producing an illusion of reality is greatly affected by sound volume. 
If the recording has been well done, and if the theater apparatus 
is in good condition, the picture may still be poorly shown if the 
sound volume is improperly handled. This is clearly a matter of 
showmanship, and must be studied as such. The definition of suit- 
able volume is simple. It is the volume at which the desired illusion 
is obtained. The illusion of reality which results from such a com- 
bination of sound and scene is such that little imagination is re- 
quired to think of the scene as being real. The attainment of this 
result is the goal of all sound picture productions. 

In real life our personal and inherited experience produces the 
effect more or less automatically. Involuntarily, we correlate the 
impressions we receive and equally involuntarily, we adjust our- 
selves to the natural distortions in every-day phenomena. However, 
an artificial device, such as a recording and reproducing system ac- 
companied by a motion picture, has no such involuntary reactions. 
It has certain potentialities which may produce amazingly good re- 
sults, but it must be guided throughout every step or some form of 
distortion will appear. If we are to show to our audiences a product 
which will, without effort on their part, give the illusion we plan, 
this guidance must come from both producer and exhibitor. The 
studio must anticipate the problems of the theater, and the latter 
must endeavor to exhibit the product in a manner approaching 
that designed by the producer. This combination alone will result 
in a high average success in terms of audience appreciation. 

Technical perfection may be analyzed in terms of scientific laws 
which are common property. There is general agreement on the 

* Metro-Goldwyn-Mayer Studios, Culver City, California. (Read before 
the Society at Washington.) 

53 



54 WESLEY C. MILLER [J. S. M. p. B. 

fundamentals, but due to the newness of sound reproduction on its 
present scale there is a tremendous lack of understanding of some 
of the details. This is naturally less apparent in the studios and 
among the producers, as they are closer together geographically, 
and as they were the first to have to meet the problems of the new 
business. Largely through their own initiative and by their own 
analysis of the situation, they are for the moment in the position 
of being able to help the exhibitor to get the results both desire to 
please the audience. Among other things, they are trying to do 
this by the expedient of making proper sound reproduction as nearly 
automatic as possible. 

Sound volume is definitely interrelated with frequency response 
of records and apparatus, theater and studio acoustics, sound per- 
spective, personal desires, and a multitude of other factors. Elimi- 
nating all of these for the purpose of the present discussion, volume 
control presents a particular problem. The total range of volume 
to which we are accustomed in real life is tremendous, and quite 
beyond the possibilities of any known commercial reproducing de- 
vice. Fortunately, this is not an impossible limitation. In the 
first place, we shall probably never wish to reproduce in a theater 
the loudest sounds we can feel or hear, as they would be uncomfortable 
to an audience. Similarly, the lowest sounds we reproduce must 
be loud enough to be somewhat audible over the theater noise 
breathing, rustling of clothes, and general movement. Conse- 
quently the total range to be accommodated is reduced to a point 
where it is entirely practicable to take care of it. 

This range, however, still exceeds the capabilities of the record 
itself. In recording we have two definite limits an upper limit 
represented by the overload point of the recording device and medium, 
and a lower, which is the inevitable surface noise in a record of any 
kind. Exceeding the upper limit introduces disagreeable distor- 
tion without noticeably louder apparent volume. Going below the 
lower limit results in a loss of part of the record by the masking effect 
of the surface noise. Every sound recording technician is continually 
making use of various devices to get the most effective results from 
this limited recording volume range. 

Fortunately there is available a means of somewhat extending 
this range in reproduction, through the medium of adjustable am- 
plification of the record. By means of this we may amplify some 
parts of the record more than others, and produce the effect of an 



July, 1930] VOLUME CONTROL BY SQUEEZE TRACK 55 

over-all range greater than the recording range proper. Even this 
available increase is limited, as too much additional amplification 
brings forth other troubles from excessive surface noise, machine 
noise, and perhaps amplifier or other system overloads. Judiciously 
used, this factor of additional adjustable amplification is a means 
of greatly enhancing the effectiveness of the reproduction. 

In recording we plan to make use of this extension when necessary. 
Ordinarily the attempt is made to have a record run without such 
a change, and the great majority of records fall in this class. But 
when we do have to use the additional amplification in the repro- 
duction, the operator must know when to use it, and, more impor- 
tant, must use it. Therein lies a weakness which has resulted in 
many a poor reproduction. 

The theater operator has at his command some form of volume 
control a fader or similar device. If cues are furnished with the 
picture he can control the volume by following these cues with the 
fader, but if the fader is in the projection booth he has no way of 
checking the resulting effect in the house, unless by reports from an 
observer. Fair results may be obtained by such a mechanical 
method. However, the average operator in a booth has plenty to do 
during the showing of a picture changing reels, watching lamp adjust- 
ment, etc. The result is that his attention to the fader must suffer. 

In certain cases the Metro-Goldwyn-Mayer organization has advo- 
cated the use of a fader installed in the auditorium and operated 
by a special operator, who is then in a position to know exactly how 
the picture sounds and to regulate the sound accordingly. This 
has produced excellent results but it has certain disadvantages, 
not the least of which, from the theater standpoint, is the require- 
ment of an additional operator who must necessarily be something 
of a sound expert and artist, in addition to his other attainments. 

These are real problems to both producer and exhibitor in the 
face of an annual release of some hundred million or more feet of 
pictures each year, involving thousands of the theaters. With them 
in mind the Metro-Goldwyn-Mayer sound organization has evolved 
a means of practically automatic volume control for variable density 
film release, which has been very effective in practice. From the 
appearance of the sound track which it uses the name of "squeeze 
track" has come into use. 

It is a well known fact that the sound volume resulting from a 
given variable density sound track record varies as the track width 



56 



WESLEY C. MILLER 



[j. s. M. p. E. 



changes. This feature is used for volume control. Due to the 
width of the reproducing aperture, the effective normal track width 
is 0.080 inch. Reducing this width to 0.020 inch gives a reduction 
in volume of 12 db. Moreover, the surface noise to signal ratio re- 
duces in practically the same ratio, that is, the effective surface noise 
is reduced in proportion to the sound on the record. If, then, we 
make our average volume track 0.040 inch wide by matting out half 
of the regular track, we may, by varying the width of the mat, get 
an increase or decrease of 6 db. by making the track 0.080 inch or 
0.020 inch wide, respectively. This is the principle of the Metro- 
Goldwyn-Mayer "squeeze track." 




Figure illustrating the principle of the "squeeze track." 



In practice, recording is done as usual and the attempt made 
to keep the recorded level as nearly uniform as is consistent with 
the desired effects. If, through some error of judgment, or because 
of the nature of the scene, a change in fader setting becomes neces- 
sary, the mat width in the release print is changed in the proper 
direction to produce the desired result. Inasmuch as the normal 
track will produce but half the volume of an unsqueezed track it is 
of course necessary to run the theater fader 6 db. higher than normal, 
but this imposes no hardship. 

In operation each reel is handled as a separate unit, and the volume 






July, 1930] VOLUME CONTROL BY SQUEEZE TRACK 57 

adjustments throughout the reel length are adjusted to keep within 
the limitations of recording volume range and squeeze mat range. 
Many reels require no squeeze mat because the range in them is 
such that the normal recording range is sufficient. In the theater 
then if the" operator adjusts any part of a given reel to the proper 
volume level the remainder of the reel is automatically right. In 
other words, if he sets the fader right for the beginning of the reel, 
the rest takes care of itself one fader cue per reel. 

Some judgment must still be used by the operator or an apparent 
necessity for cues results. In the studio the right balance is es- 
tablished between the loud and soft parts of the reel. If now the 
operator runs the soft parts, such as low dialog, at too great a level, 
the loud parts will run much too loud and must apparently be cued 
down. There is a tendency in most theaters to run the dialog ab- 
normally loud, so that in making the mat this must be taken into 
account. The result is that we often find ourselves in possession of 
a usable volume range which is too great for theater use. This 
paradox will correct itself as time goes on, and as a better under- 
standing of proper volume is gained by the operator. 

In the accompanying figure is shown a short section of sound 
track with a rapid change from full volume down to minimum vol- 
ume. This rapid transition is shown for illustration only, as the 
changes are much more rapid than practice demands, although they 
are entirely practical if such rapid changes are required. It will 
be noticed that the sound track appears between two mats. Con- 
sideration of the reproducing apparatus will show the reason. The 
lateral adjustment of the apparatus may not be quite correct, but 
the relation between track and black area will still not be varied. 
This is of course essential. It is expected that the apparatus will be 
in adjustment, but this method of applying the squeeze mat offsets 
slight adjustment irregularities. 

The production of the squeeze mat on release prints may be ac- 
complished in several ways, modification of printer apertures and 
double printing with a negative mat being the most readily applicable 
to present commercial practice. Projection printing methods also 
offer possibilities. Each of these has been tried and satisfactory 
results obtained. The production of the original matrix or mat 
is also something of a problem, but suitable automatic control de- 
vices have been developed which work admirably. Later publi- 
cation of their details is contemplated. 



58 WESLEY C. MILUSR [J. S. M. p. B. 

This type of volume control has been in use for several months 
wherever the volume requirements have been such as to require it. 
Comments from the field have been uniformly favorable, especially 
since the operation of the device has become better understood by 
operators. Fader cue sheets still accompany each picture, but dis- 
regard of the instructions which they contain has had a less deleterious 
effect than in the past. If any part of a reel is set to give the right 
volume the rest is automatically correct. If the volume is set for 
dialog the high spots are found to be colored as they were designed 
to be. The adoption of the device has enabled the producer to 
more nearly obtain in the theater the result which he put into the 
picture, and his average of technical and artistic success has improved. 
The operator is relieved of the difficult problem of constantly watch- 
ing the fader cues. The net result has been a very gratifying advance 
in the production of the much sought after illusion which the audience 
can enjoy and will appreciate. 

DISCUSSION 

MR. SHEA: Is the method suggested applicable only to variable density 
recording? 

MR. RICHARDSON: The squeeze track method is only applicable to variable 
density. 

Means are being developed to put the control in the viewing rooms, so that 
as the director and his musical directors are studying their production they can 
fade and adjust the sound levels to suit their own ideals. 

MR. EVANS : In connection with the work we have been doing in the Standards 
Committee on wide film, we propose a 250 mil sound track. The principal 
arguments for this are that by widening the sound track you improve the ratio 
of signal to sound track ground noise. This squeeze track method, it would seem, 
goes in the wrong direction. 

MR. RICHARDSON : We realize that a scratch on this track will produce worse 
results than one on the full width. Beautiful productions, however, are often 
ruined by poor control in the theater. You have the two horn dilemma and 
the squeeze track seems the best way out. 

MR. Ross: Supplementing the reply to the question raised whether this 
system is limited to the variable density system, I wish to state that the sound 
volume level of the variable area system can be varied by variably light fogging 
the sound track. In fact the variable density sound track may also be variably 
light fogged to accomplish the same result as squeezing the track. 

MR. COFFMAN: Contrary to Mr. Evans' belief, it seems to me that the wide 
sound track is needed to make this system fully effective. With 250 mils, you 
can squeeze it to a greater degree than you can in the present size print, and you 
will have more control than the 12 db. of the present system. 

MR. TOWNSEND: Speaking of control with variable area sound track, it may 



July, 1930] VOLUME CONTROL BY SQUEEZE TRACK 59 

be of interest to point out that there is in operation an automatic system of regu- 
lating the sound track on variable area film. Two productions made with this 
method are about to be released. The process is very simple. It is done auto- 
matically at the time of recording. Without modulation, there is no sound track 
whatever. As the modulation increases to any magnitude, the sound track 
automatically appears even up to the full width of a wide film sound track, which 
is 250 mils. 

MR. Ross: I should like to state as a matter of interest that a new company 
has recently introduced a system of automatic control for motion picture theaters 
which dispenses with the services of a projectionist. Part of this system includes 
automatic sound volume level control. A microphone is placed in the audi- 
torium which controls the fader in the horn circuits. 

MR. MAURER: As a slight contribution to this general discussion, those of 
you who will remember one of the figures in my paper (/. Soc. Mot. Pict. Eng., 
June (1930), p. 640) will recall that if you start with a negative of relatively 
low density and overprint it, the volume level drops rapidly, but the ratio of 
signal to ground noise remains the same. Also there is practically no change in 
quality. Starting with a negative of density about 0.8 and working through the 
range of exposure in which the resolving power is best, one can get a ten to 
twelve decibel range of volume control without change of quality simply by 
varying the printer lights in printing the sound track. This has not been put 
into practice, but it could be handled readily on the basis of facts already available. 



THE MEASUREMENT OF LIGHT VALVE RESONANCE BY 
THE ABSORPTION METHOD 



O. O. CECCARINI* 

In investigating the behavior of electro-mechanical systems the 
method which invariably seems to be readily applicable is that of 
measuring the effect by a disturbance of known character and mag- 
nitude applied to the system. Sometimes it is far more simple and 
economical, especially when we are concerned only with qualitative 
measurements, to observe not the final effect but the reaction of 
the system to the flow of energy supplied by the source. 

In sound recording on film the light valve plays a very important 
role, and to its correct adjustment depends largely the uniformity 
and quality of results. Below resonance, the light valve is a con- 
stant amplitude device, but not at resonance nor beyond resonance. 
It is therefore necessary that its resonant frequency be well outside 
the useful range. In addition, the sensitivity of the light valve is 
very much dependent on the tension with which the ribbons are 
stretched, as an excessive tension, and therefore a high tuning point, 
lowers the valve response to an appreciable extent. It is therefore 
very essential that the frequency of resonance be carefully deter- 
mined, and kept within certain limits to insure uniformity. 

Let us review briefly the various steps in recording sound on film. 

Sound waves converted into electric waves by the condenser 
transmitter, are amplified to a sufficient amount and fed to the 
light valve. 

The Western Electric film recorder, as familiar to many, consists 
of an exciting lamp, condenser, light valve as part of an electro- 
magnet, optical system, film, sprocket, photo-electric cell, and ampli- 
fier for monitoring. Other mechanical parts do not concern us here. 

If, instead of the electric waves from the amplifying system, we 
supply the light valve with constant volume from a variable oscillator 
and connect a volume indicator at the output of the photo-electric 

* Metro-Goldwyn-Mayer Studios, Culver City, California. (Read before the 
Society at Washington.) 
60 



MEASUREMENT OP LIGHT VALVE RESONANCE 61 

cell monitoring amplifier, we will be able then to detect any change 
in response in the light valve for any frequency within the range 
of the oscillator. As we enter the resonance range the light valve 
becomes more and more sensitive, and will vibrate at far greater 
amplitude than at any other value of the frequency. Our volume 
indicator will therefore show greater response, and any change in 
the mode of vibration of the light valve will be faithfully interpreted 
by the volume indicator. 

This is the most obvious method for tuning and checking the 
tuning point of the light valve, and the method adopted by the 
Western Electric from the very beginning and prescribed to the 
various studios using Western Electric apparatus. There is noth- 
ing wrong with this method except that it involves tying up a film 
recording machine, a very costly piece of apparatus. Also it is 
difficult to arrange the apparatus in one place, and therefore it can- 
not be readily called a one man job. 

Bell System engineers realized the disadvantages of the arrange- 
ment and proceeded in designing the light valve tuning unit, which 
is now supplied as regular equipment and contains in miniature 
practically all of the above apparatus. 

This unit has undoubtedly greatly facilitated the task of keeping 
the valves in proper shape, but the writer does not agree that it 
constitutes the most economical arrangement which engineering 
ingenuity can produce, especially when there are other phenomena 
directly linked with the operation of the light valve which can be 
utilized for the purpose, such as, for instance, the reactive voltage, 
or counter emf., generated by the motion of the light valve ribbons 
in a magnetic field. This particular phenomenon is of a fundamen- 
tal nature and well known to any student of engineering and physics 

The counter emf. set up in a conductor is proportional to the 
rate at which the conductor cuts the magnetic field. The equilib- 
rium position assumed by the system for a given value of the 
driving current is dependent upon the value of the current, the ex- 
citing field, the elasticity, the mass, and the dissipative constants 
of the electro-mechanical system. It is easy to see how a change in 
any of the constants would change the equilibrium position. At 
resonance the elasticity neutralizes the effect of the mass and the 
valve tends to vibrate at much greater amplitude. This greater 
amplitude in turn means greater counter emf., which, being entirely 
opposite to the driving voltage and current, tends to limit the latter 



62 



O. O. CECCARINI 



[J. S. M. P. E. 



vwv 



and a new equilibrium position is reached by the system at which 
the driving current is appreciably less than for a non-resonant con- 
dition. 

For the electrical engineer the 
system can be represented by the 
circuit of Fig. 1, in which a source 
of voltage drives a current through 
a parallel circuit of constants, r, L, 
C, supposed to represent the light 
valve vibrating in a magnetic 
field. The resistance, r , is that of 
the source, and r x is that of a 
measuring instrument. 

The voltage equation for the system in symbolic form can be 
written down at once: 




FIG. 1. 



e = 




...(1) 



r 



and for unity emf. the value of the driving current becomes: 



( 



...(2) 



At resonance we have the condition: 



PL + = 



and, 



^ 1 = 



(3) 



(4) 



We could perhaps see a little more readily what happens at reso- 
nance if we would assume the valve free from dissipative constants. 
In other words, r = o. It is readily seen, from equation (4), that 
i\ becomes o. We would say then that the counter emf. is equal 
in magnitude and opposite to the driving voltage across the valve. 



July, 1930] MEASUREMENT OP LIGHT VALVE RESONANCE 63 

This condition is never realized in practice, but the driving current 
always becomes appreciably less, and the drop can be readily mea- 
sured. Our measuring instrument would then indicate a dip at reso- 
nance instead of the peak shown by the volume indicator with the 
Western Electric method. 

It is interesting to note here that the only equipment necessary 
to tune a light valve by means of what we can call the absorption 
method is a variable oscillator, a suitable thermocouple in series 
with the valve, a microammeter to measure the voltage developed 
by the couple and an electromagnet with an exciting coil of the 




FIG. 2. Laboratory model of resonance measuring instrument. 

'orm used in the film recording machine, but very much simpler since 
no light passage through it is necessary. 

From the foregoing it is quite evident that the absorption method 
s simpler and quicker in operation than the other method. Another 
point of great advantage is that it is not necessary for the operator 
to know the principle and details of the tuning outfit, because the 
number of operations necessary can be reduced to a single switch 
to energize the oscillator, another switch to turn on the exciting 
current for the electromagnet and 180 degrees rotation of the condenser 
dial to cover the entire frequency range froih 4800 to 10,000 cycles. 



64 



O. O. CECCARINI 



[J. S. M. p. E. 



The included photograph (Fig. 2) shows the first model made 
up at Metro-Goldwyn-Mayer Studios. This model has been con- 
tinuously in service for the past eighteen months. The photograph 
for the model made up for use with movietone trucks for location 
work is also given (Fig. 3). 

The following is a brief description of the variable oscillator: 

In order to cover the greatest possible range with the minimum 

amount of variable capacity, it is necessary to operate the oscillating 

coil very close to its natural period. Instead of designing a coil 




FIG. 3. Portable model for use with trucks in the field. 

especially for the purpose, the writer chooses to make use of the 
Western Electric 91-A retardation coil. This coil has two wind- 
ings, each of which has a natural period slightly above 5000 cycles. 
In order to bring the upper frequency range above 10,000 cycles 
two 91-A coils are connected as shown in Fig. 4. 

The resistance, R , of the order of 20,000 ohms is inserted in 
series with the grid coil to prevent the system oscillating on the 
grid side. Fig. 5 gives the complete schematic arrangement of the 
oscillator amplifier and valve measuring circuit. 



July, 1930] MEASUREMENT OF LIGHT VALVE RESONANCE 



65 



It will be noticed in the above arrangement that no "C" battery 
is used for the oscillator grid, nor for the amplifier grid. The reason 
for this is that the distortion caused by the oscillator tube is com- 



l 
Grid 



I* 
.42 

82 

oc 

|2 




Thi* 5ccHon of coil *Z 
is tio4 u-scd 



ii 

a. 



3 



31 A Retardation 



Fixed Condenser 
limiting upper fraaucnoj 
range 



FIG. 4. Arrangement of oscillating circuit. 



O3ctuuATX>it AMPLirie* 




A 6 

FIG. 5. Schematic circuit of tuning unit. 



66 



O. O. CECCARINI 



[J. S. M. P. E. 



pensated by that of the amplifier, and the resulting wave at the 
output of the amplifier is exceedingly pure. This balancing effect 
is true only with vacuum tubes of a certain type and characteristic, 
and not general. Caution must therefore be exercised. 

The thermocouple which has been found most convenient for 
the purpose is the Western Electric type 22-B, having a heater re- 
sistance of approximately 40 ohms, and for a galvanometer the 
Weston model 322 (200 microamperes, 10 ohms) is eminently satis- 




FIG. 6. Comparison of resonance determination by two methods. 



factory, although a more economical type, such as the General 
Radio pointer type galvanometer (10 ohms, 150 or 160 microamperes) 
is quite satisfactory. 

It must be pointed out here that calibration of the thermocouple 
and galvanometer is not necessary unless quantitative data are 
required, which is seldom the case. For illustrative purposes, Fig. 6 
gives the resonance response characteristic of a typical light valve, 



July, 1930] MEASUREMENT OP LIGHT VALVE RESONANCE 67 

both by the absorption method and by the direct response method. 
It will be noticed that the two characteristics are strictly related 
to each other. 

In concluding, the writer believes to have satisfactorily proved 
the advantages of the absorption method for tuning light valves, 
especially with regard to simplicity and economy of apparatus in- 
volved. 

A little consideration will readily bring in evidence of the fact 
that this method measures strictly the "admittance function" of 
the electro-mechanical system, and therefore it can be also applied 
to the investigation of the performance of loud speakers, condenser 
transmitters, and other electro-dynamical apparatus involving the 
motion of conductors in electromagnetic or electrostatic fields. 



PROGRESS IN THE MOTION PICTURE INDUSTRY* 

The most significant events of progress for the fall and winter 
of 1929-30 have been the increased production of feature pictures 
combining sound and color, and the marked improvement in sound 
quality and in picture artistry. The technical quality of color 
pictures, however, still leaves much to be desired and further im- 
provements must be made before the full benefit of color will be 
realized. 

Production of pictures on film wider than 35 mm. has not gone 
ahead as rapidly as predicted chiefly because of the lack of an agree- 
ment on a definite standard for such film. Pending an agreement, 
the majority of the producers are marking time, thus indicating 
their willingness to collaborate in adopting a standard. Widths 
of 70 mm. and 65 mm. are most favored. A subcommittee of the 
Standards Committee of this Society, consisting of the chief engi- 
neers of all the leading producing organizations, is working on this 
important problem. 

Sound recording studios are working on smoother production 
schedules as the problem of recording has become more a matter 
of routine. Production programs for feature sound pictures are 
in progress in England, France, and Germany. The trend in new 
construction is toward larger sound stages which can be divided 
up or opened out as required. Most of the tricks of the silent pic- 
ture, fades, dissolves, double exposure, etc., have been worked out 
by cameramen while under the pressure of actual production. Valu- 
able surveys are being made more deliberately relative to causes of 
camera noise, silencing of arcs, release print specification, screen 
illumination, and set acoustics. 

A census made in Hollywood during January, 1930, indicated that 
about 40 per cent of the leading studios were using arcs for 50 per 
cent or more of their productions. One of the leading color picture 
processes was stated to favor arc illumination. Incandescent lamps, 
however, have continued to find general favor and improvements 
in their design and installation have been noted. 

* May, 1930 Report of the Progress Committee. (Read before the Society 
at Washington.) 
68 






PROGRESS IN MOTION PICTURE INDUSTRY 69 

The problem of acoustics of studios and auditoriums is being 
investigated very thoroughly. Results of a survey of more than 
1500 theaters have been reported. Engineering measurements indi- 
cate that the increased acoustic power available with electrical 
amplifying currents introduces new factors for which quantitative 
data are not yet available. 

Improvements have been noted in cameras, printers, processing 
machines, and projectors. Attention is being given to the impor- 
tant problem of film storage as processing laboratories appreciate 
the seriousness of the danger involved. The increased hazards 
resulting from the use of high intensity arcs for sound film projec- 
tion have been reduced materially by the introduction of rear shutter 
projector assemblies. 

Motion pictures in sound are beginning to be used in conjunction 
with education, business, medicine, and for legal records. The 
availability of portable recording and reproducing equipment and 
a general lowering of costs of other sound equipment no doubt have 
encouraged this development. 

No significant improvements have been noted in stereoscopic 
cinematography but methods of television continue to develop. 
One type of television receiver utilizes a fluorescing screen within 
a cathode ray tube which permits a reduction in the number of 
images per second without noticeable flicker. Technical difficul- 
ties of television may take years for their solution, however, especially 
with wireless transmission and reception for pictures. 

Acknowledgment. It was considered desirable, because of the 
growth of our Society abroad, to invite several members and others 
doing motion picture work in foreign countries to assist in the work 
of the Progress Committee. The assistance rendered by these 
foreign members and friends has been very valuable. Two of them 
made such interesting and comprehensive reports that their papers 
have been recommended for publication in our JOURNAL. They 
represent reviews of cinematographic progress in France and Austria, 
respectively. Excellent reports have also been received from Eng- 
land, Germany, Switzerland, and Australia. 

Acknowledgment is also made to Dr. J. B. DeLee and the Fox 
Film Corporation for the loan of a sound film of an obstetrical opera- 
tion, and to Frank Woods, N. D. Golden, and L. Trotti, for the use 
of copies of publications of their respective organizations. A num- 
ber of interesting films, particularly newsreels of outstanding events 



70 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. E. 

of the past six months, have been lent for showing by the Fox Film 
Corporation, Universal Pictures Corporation, and the Paramoimt- 
Famous-Lasky Corporation. H. Rosenberger has contributed a 
film which includes two examples of his remarkable photomicro- 
graphic work on living cell tissues. Sound picture records of several 
of the world's leading scientists have been made available through 
the courtesy of the General Electric Company. 

Helpful data have also been received from the following: L. P. 
Clerc, H. Griffin, W. H. Peck, G. K. Rudolph, and V. Zworykin. 

Respectfully submitted, 

M. ABRIBAT A. W. DANASHEW A. C. HARDY 

J. A. BALL J. B. ENGL R. C. HUBBARD 

J. BOOLSKY R. E. FARNHAM G. F. RACKETT 

W. CLARK H. B. FRANKLIN S. K. WOLF 

K. GEYER 
GLENN E. MATTHEWS, Chairman 

SUBJECT CLASSIFICATION 
I. PRODUCTION 

A. Films and Emulsions 

1. New Materials 

2. Manufacture 

3. Miscellaneous 

B. Studio and Location 

1. General 

2. Studio Construction 

3. Lenses and Shutters 

4. Cameras and Accessories 

5. Exposure and Exposure Meters 

6. Studio Illumination 

7. Make-Up, Actors, and Direction Technic 

8. Trick Work and Special Process Photography 

9. Methods of Recording Sound 

C. Laboratory Practice 

1. Equipment 

2. Photographic Chemicals and Solutions 

3. Printing Machines and Methods 

4. Editing and Splicing 

5. Titles 

6. After Treatment, Cleaning, Reclaiming, and Storage 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 71 

II. DISTRIBUTION 

III. EXHIBITION 

A. General Projection Equipment 

1. Projectors and Projection 

2. Sound Picture Reproduction 

3. Projector Lenses, Shutters, and Light Sources 

4. Fire Protection 

B. Special Projection Methods 

1. Portable Projectors 

2. Stereoscopic Projection 

3. Continuous or Non-intermittent Projection 

C. Theater Design and Installation 

1. Screens 

2. Theater Illumination 

3. Theater Acoustics and Construction 

IV. APPLICATIONS OF MOTION PICTURES 

A. Education, Business, and Legal Records 

B. Medical Films, Radiography, and Photomicrography 

C. Telephotography and Television 

D. General Recording, Miscellaneous Uses 

V. COLOR PHOTOGRAPHY 

A . General 

B. Additive Processes 

C. Subtractive Processes 

VI. AMATEUR CINEMATOGRAPHY 

A. General Equipment and Uses 

1. Cameras 

2. Projectors 

3. Accessories 

4. Scenarios 

5. Films and Film Processes 

B. Color Processes 

VII. STATISTICS, PUBLICATIONS, AND NEW BOOKS 



72 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. P. E. 

I. PRODUCTION 

A. Films and Emulsions 

Increased interest has been noted in the past six months in the 
subject of wide films. Of the widths proposed, 70 mm. and 65 mm. 
appear to have received the most consideration. The producing 
organizations fully appreciate the importance of the engineering 
problems involved in the introduction of wide film and are post- 
poning definite action pending a decision of the subcommittee of 
the Standards Committee of this Society, the personnel of which 
includes engineers from all the producers. A limited amount of 
production, however, has been undertaken on film 70 mm. wide. 
A feature, Happy Days, and a newsreel were shown as a regular 
program, opening March 14th, at the Roxy Theater on a screen 4iy 2 
feet by 22 feet. 1 Several other theaters are also equipped to handle 
this type of film and at least four feature pictures are said to be 
in progress. 

The optical problems arising in the development of wide film have 
been considered by Ray ton. 2 Howell and Dubray 3 discussed prac- 
tical and artistic elements bearing on the selection of wide film 
standards. They proposed a three to five ratio of height to width, 
placement of the sound record to occur outside the sprocket holes, 
and rounded corners for the perforations. Jones 4 made an exhaus- 
tive analysis of the sizes of the paintings of one of the old masters, 
Rubens, and tabulated the rectangular proportions for different 
forms of composition. A rectangle having a width to height ratio 
of 1.618 is considered by many artists to be one of the best shapes 
for a pictorial composition. Gregory 5 has written on the early 
history of wide films. 

Sound motion pictures in color have come into still greater use 
and are regarded by several authorities as the most outstanding 
development of the year. Five processes have been exploited and 
the entry of a sixth process, both on standard 35 mm. film and wide 
film, has been announced. 6 Definite advances in optical systems, 
processing methods, and the experience that follows production 
problems on a large scale have all contributed to a substantial im- 
provement in the quality of color pictures. 

The bulk of the raw film being used is coated on nitrate stock 
although the hazard resulting from improper and careless storage 
of this stock has been demonstrated forcibly by the results of a num- 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 73 

ber of serious film fires during the year which destroyed many valuable 
negatives. A large English firm manufacturing a non-inflammable 
support is reported to have found difficulties in applying emulsions 
to the base and has decided to sell the uncoated product on the 
open market. 7 A raw film factory with a daily production capacity 
of sixty thousand meters is reported to be in operation in Tiflis, 
Russia. 8 

About the usual large number of patents have been issued relating 
to cellulose acetate compositions, indicating continued attention 
of the manufacturers to this important development. In view of 
the limited interest in the details of these, reference to the patent 
numbers has been omitted from this report. The references can 
easily be found by consulting the issues of the Monthly Abstract 
Btdletin, published by the Kodak Research Laboratories. A few 
patents have appeared dealing with methods and machinery used 
for roll coating of film support. 9 Protection has been granted the 
idea of incorporating a light sensitive material in a cellulose xanthate 
or viscose film base. 10 

Patents of interest dealing with emulsion manufacture describe 
a device for double coating a film support, the incorporation of a 
hygroscopic substance in an emulsion to accelerate subsequent 
development with gases or vapors, a process for coating an emul- 
sion to equal thickness on uneven bases, and the addition of protein 
substances to emulsions to enhance sensitivity. 11 

Of particular interest is a German patent which disclosed a process 
of light sensitive emulsion manufactured without the use of silver 
salts. 12 Certain compounds capable of undergoing stereo-isomeric 
changes under light action are mixed with gelatin, collodion, or cello- 
phane, and coated as a photographic layer. If one of the stereo- 
isomers is colored and the other is colorless, an image is produced 
immediately on exposure. 

The addition of a sound record on motion picture film in conjunc- 
tion with the picture has increased the necessity for a more thorough 
understanding of the characteristics of film. Toward this end, 
Schmidt 13 has contributed a paper discussing the photographic 
relations of density, transparency, and contrast of negative and 
positive films having variable density sound records. At the Toronto 
meeting, Jones and Sandvik 14 dealt with the photographic char- 
acteristics of sound recording film giving the results of practical 
tests on several different emulsions. Sensitometric characteristics, 



74 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. P. E. 

resolving power, contraction, and growth of images were discussed. 
Conklin 15 has described the use of a set of transparencies which 
may be superimposed on a sensitometric (H. & D.) curve for rapid 
determination of the characteristics of the emulsion under investi- 
gation. 

Patents relating to sound film emulsions dealt, among others, 
with the following methods: The preparation of a tinted film having 
a narrow uncolored strip along one side on which the sound record 
may be printed; several patents by Gaumont cover their method 
of making sound records reproducible only by ultra-violet radiation. 16 

The importance of pitch measurement in film perforation has 
been treated by Carson 17 in the JOURNAL of this Society. Several 
patents 18 have been taken out on methods of reenforcing the edges 
of film strips, on anti-static layers in film, and on edge printing. 

B. Studio and Location 

The major portion of the motion picture studios in the United 
States had been equipped for sound recording by the end of 1929 
and new studios built by the leading producers. The trend is toward 
large sound-proof structures that may be opened into one another 
for large exteriors, long shots, and reviews. Two huge sound stages 
have been completed in Hollywood recently by two producers. 
One of these stages is 150 feet wide by 500 feet long and five stories 
high; it is divided into four parts and when opened will house a set 
occupying 75,000 square feet. Overhead monorail systems facili- 
tate the movement of sets. 19 The other stage has been conceived 
on equally gigantic proportions and comprises a theater auditorium 
capable of seating 1500 persons and a section which is also designed 
as a theater stage; in size, 75 feet deep, 80 feet wide, and-120 feet 
high. This stage has been designed particularly for the production 
of lavish spectacles. It is equipped with a steel curtain weighing 
65 tons, and each of its 12 floor sections is fitted with a hydraulic 
lift. A vertical steel track, 65 feet high, permits camera shots in 
synchronism with the rising stage and curtain. 20 

In order to standardize the quality of motion pictures and to elimi- 
nate matter from scenarios which would prove objectionable to the 
public, the Association of Motion Picture Producers and the Hays 
organization drew up and approved a production code. 21 In the 
immediate practical field, Pfitzner has considered the economics 
of studio management. 22 The requirements for the ideal sound 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 75 

studios have been discussed by Schultz. 23 The increased use made 
of incandescent lights has necessitated the installation of refrigera- 
tion plants in studios in connection with ventilation systems. 24 
Ground vibration noises are claimed to be minimized by the use of 
"floating floors" resting on a base of sound absorbing material and 
not connected to the outside walls. 26 

A description has been published of a new sound studio located 
at Wembly, England. 26 Its largest stage is 120 feet by 90 feet in 
size. Floors are laid on felt runners with a layer of plastic bitu- 
men under the boards. A novel feature of this studio is a tank fitted 
with a camera booth permitting underwater photography. The 
four new German studios at Neubabelsberg have been built in the 
form of a cross, all recording and monitoring being done at the center. 27 
A number of French studios are now producing sound pictures ac- 
cording to reports from France, notably those located at Joinville, 
Epinay, and Paris. One French studio operating at Courbevoce 
was destroyed by fire early in February. 

New studios have been reported under construction near Moscow 
by Danashew who stated that the largest containing 5 stages would 
have 175,000 cubic meters of space. 28 

Lenses and Shutters. The characteristics of a new f/2.7 80 mm. 
lens for soft focus effects were tested by Emmermann and Seeber 29 
both for arc and incandescent lighting. Noulet 30 has described 
two methods for introducing aberration in lenses. The introduction 
of color motion pictures has made greater demands on the performance 
of lenses, particularly in the photographing of long shots. A novel 
lens device for securing wider pictures without the use of wide film 
is of interest. 31 It consists of two lenses held in a mount which 
screws onto the front of the camera. A lateral compression of the 
image is produced so that nearly three times as much image is in- 
cluded in the normal frame. The picture is then expanded to three 
times normal width on projection. 

Patents dealing with lenses and shutters 32 have been noted relating 
to a method of producing relief effects by alternate exposures through 
a system of lenses and mirrors, a device for prevention of the picture 
getting off center, and an apparatus for simultaneously taking de- 
tails of foreground and background. In the last named patent 
this is accomplished by oscillating mirrors placed behind a dual ob- 
jective system in the camera. 

Cameras and Accessories. Stull 33 described changes made in the 



76 PROGRESS IN MOTION PICTURE INDUSTRY [j. S. M. p. E. 

Mitchell camera to adapt it for use with 70 mm. film. The shutter 
size is doubled, and the gears are cut differently to adapt them to 
the pitch of the perforations which is stated to be 0.231 inch for 70 
mm. film. 

The French camera, "Eclair," was described by Eveleigh. 34 Its 
features are: lightness, a six lens turret, a direct vision tube sight, 
and an automatic fade. A new model of the Askania camera ap- 
peared which is equipped for single, normal, and ultra-rapid ex- 
posures. 35 The Castagna camera, manufactured in Vienna, is housed 
completely in an all metal case (Fig. 1). It is fitted with a four 




FIG. 1. Castagna motion picture camera (Vienna, Austria). Reproduced by 
courtesy of Dr. P. Schrott, Vienna, Austria. 

lens turret, and the front may be swung open providing easy access 
to the gate. The shutter design is novel in that a fade may be ad- 
justed to a definite number of crank turns from a minimum sector 
opening of 5 degrees to a maximum of 180 degrees. 

Fear 36 designed a silent high speed movement for Bell and Howell, 
and Mitchell cameras. Pilot pins, accurately fitted, lock the film 
while the shutter is open and an eccentric has been substituted for a 
cam for moving the film. More recently, the same inventor intro- 
duced a completely new silent camera which is stated to be adaptable 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 77 

quickly to color motion pictures, sound-on-film photography, and 
wide picture photography either on wide film or by the Fear proc- 
ess which rotates the images through an angle of 90 degrees, placing 
the frames longitudinally on 35 mm. film. 37 

According to a well-known motion picture director, the use of syn- 
chronous electrical camera drives, necessitated by simultaneous 
longshot and close-up exposures in sound motion picture work, 
has freed first cameramen from actual cranking and given them 
more time to consider pictorial composition. 38 Cowan 39 reported 
on a survey of camera and projection apertures in relation to sound- 
on-film pictures. A joint committee of the Society of Motion Pic- 
ture Engineers, the Academy of Motion Picture Arts and Sciences, 
the American Society of Cinematographers, and the American Pro- 
jection Society prepared a resolution on recommended practice for 
cameramen and projectionists. This resolution was recommended 
as standard practice by the Standards Committee of the Society 
of Motion Picture Engineers at the Toronto meeting in October, 
1929. Essentially the resolution suggested that a rectangle 0.620 
inch by 0.835 inch be marked on the ground glass of cameras 
and that an aperture size of 0.600 inch by 0.800 inch be adopted for 
sound-on-film projection. 

Accounts have been published of cameramen's experiences in 
frigid countries, notably of the troubles encountered by Rear Admiral 
Byrd's Antarctic expedition. 40 Spring-driven cameras failed at 
20F. Lieberenz 41 was able to keep such cameras in operation 
even at 40F. by cleaning the mechanism with gasoline and 
lubricating with a mixture of kerosene and bone oil. 

A viewing device known as the "Orthoviseur" was announced 
for use on Debrie cameras. 42 It is used for determining the field 
angle and focus of the particular objective to be used on the camera, 
namely, 35 mm., 50 mm., 75 mm., and 100 mm. An erect image 
is produced about 9 cm. by 12 cm. in size and not reversed left and 
right. A focussing lens giving an enlarged view on the focussing 
screen has also been made available for the Debrie camera. Smack 43 
described the construction and properties of flexible drive shafts 
for motor-driven cameras. Chutes fitted between the sprocket 
and magazine assist in minimizing film buckling troubles, accord- 
ing to Henri-Robert. 44 Jonson 45 described a buckle-proof maga- 
zine designed for Mitchell cameras. 

The added weight of sound-proof housings has resulted in the 



78 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. E. 

design of stronger tripods. One of these called a "camera dolly" 
is constructed of telescoping steel parts attached to a triangular 
rubber tired traveling support. 46 Types of equipment and methods 
used for still photography in German studios were described by 
Lichtenstein. 47 The use of an amateur motion camera was con- 
sidered valuable by a Hollywood cameraman as an inexpensive 
means for making trial shots on sets. 48 

Many improvements have been noted in camera design as shown 
by the large number of patents 49 issued which, besides the usual 
modifications in claw pull-downs, shutters, magazines, etc., deal 
with the use of derivatives of cellulose, such as acetyl cellulose for 
the manufacture of film spools ; the obtaining of relief effects by move- 
ment of a camera round an eliptical or oval path during exposure; 
and electrical tension regulation for delivery or take-up reels. 

Time-Lapse and Ultra-Speed Cameras. An ultra-rapid camera 
known as the "Trommelapparat" employs a high frequency 
30,000 volt arc for illumination intermittently flashed on the sub- 
ject by means of a rotating sector. The film is wound on the inside 
of a cylinder which accommodates 100 turns of 40 frames each. 
Four thousand normal frames may be exposed per second, or 8000 
and 16,000 half or quarter normal frames, respectively, per second. 50 

Only two patents appeared dealing with improvements in motion 
study cameras. 51 

Exposure and Exposure Meters. A cameraman 52 recounted some 
of his experiences in making satisfactory exposures in the tropics. 
Yellow filters and panchromatic film were employed, exposures being 
made between 7:00 and 11:00 A.M. each day. Emmermann 53 de- 
scribed the properties of silk screens used before the camera lens for 
the production of diffused negatives. A light intensity meter used 
for the determination of the light values on motion picture sets, 
as well as light measurements in connection with printers and screen 
illumination, was described by McCoy. 54 The meter consists of a 
shielded photo-electric cell with a range of sensitivity of 100 to 3000 
foot candles, having a broad response covering the visible spectrum. 
A patent was issued relating to the design of an actinometer of the 
rotating wedge type. 55 

Studio Illumination. A survey of incandescent lighting in the 
United States, Germany, and England was published by Eveleigh. 56 
Two sizes of spotlights available in Germany permit variation of 
the spot diameter and utilize a front ground glass plate for obtain- 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 79 

ing uniform diffuse illumination. 57 Descriptions were published also 
of searchlights, floodlights, "spots," overhead banks, and broad- 
sides manufactured by a German firm particularly for use in the 
production of sound films. 68 

In order to decrease the heat given off by high intensity illumi- 
nants, such as used for lighting sets for sound and color motion pic- 
tures, Gordon 59 has proposed an experimental design of a water cell 
surrounding the lamp. Such a cell dissipates 75 per cent of the total 
watts input and results in only about 7 per cent light loss. Although 
it seemed that the practical limit of incandescent lamps had been 
reached several years ago when a 30 kilowatt lamp was announced, 
lighting engineers showed this was not the case, for a 50 kilowatt 
lamp was made available during the fall of 1929. 60 According to 
recent reports from Hollywood studios thirty-six inch reflectors 
have been found to give maximum effectiveness with 10 kilowatt 
incandescent lamps. The small light units, 1, P/2, and 5 kilowatts, 
found most extensive employment in studios early in 1930. Portable 
dimmers, used individually or in connected units of two or three, 
found useful application for sunrise or sunset effects. Bach unit 
handles 20 kilowatts. (Fig. 2.) 

A joint committee of the Producers and Technicians branches of 
the Academy of Motion Picture Arts and Sciences reported on an 
investigation of arc lighting in fifteen Hollywood studios. 61 In 
60 per cent of the studios, arcs were being used for less than 10 per 
cent of the lighting; in 35 per cent, arcs were used for 25 to 50 per 
cent; and in only one studio were they employed almost exclusively. 
Sun arcs and spots were finding more extensive application. Three 
types of filters were in use: (a) individual choke coils for each lamp 
unit, (b) choke coils for each group of lamps, and (c) the use of a large 
electrolytic capacity across the generator windings. The investi- 
gation is being continued with plans for making oscillograph records 
of the commutator ripple at each studio. Buck and Albert 62 pre- 
sented a paper on the subject of elimination of commutator ripple 
at the last meeting of the Society. 

Descriptions have appeared in several foreign journals of new 
styles of illuminants, particularly several designs of the Osram 
Nitrophot which is said to be especially adaptable for use with pan- 
chromatic film. 63 Controversies have raged abroad, as in this coun- 
try, on the relative merits of arc and incandescent lighting. It seems 
to be generally agreed that arcs possess many more merits to recom- 



80 



PROGRESS IN MOTION PICTURE INDUSTRY [j. S. M. p. E. 



mend their employment than when panchromatic film first came into 
extensive use in 1928. 64 

According to Clerc, 65 reflectors dyed with rhodamine and emitting 
fluorescent red light proved inadequate and too unstable as a prac- 
tical means for supplying the red rays deficient in mercury vapor 
lamps. Combinations of tungsten and mercury vapor lamps in the 
ratio of 1125 watts or 750 watts of tungsten to 400 watts of mercury 
both give satisfactory rendering on panchromatic film without a 
filter. 




FIG. 2. Portable dimmer used to create "sunset" or "sunrise' 
Reproduced by courtesy of P. Mole, Hollywood, Calif. 



effects. 



Abadie 66 reported before the cinematographic section of the French 
Photographic Society on some interesting experiments with gaseous 
illuminants. Mercury and neon could not be used effectively in 
the same tube to give a white light, but when their combined light 
was supplemented with that from vaporized antimony and arsenic, 
a good white light was produced for the photography of colored ob- 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 81 

jects. A lamp had been produced which contained neon gas and a 
cadmium-bismuth alloy at the cathode. Upon heating, the cad- 
mium was vaporized and its arc gave a light of desirable spectral 
distribution. Two new glow lamps were announced for variable 
density sound recording. 

Benford 67 presented useful, data at the Toronto meeting on the 
radiation characteristics of two mercury arcs. A carbon arc lamp 
with a chromium plated copper reflector was claimed to give an in- 
creased illumination efficiency over other lamps of similar wattage. 68 

Make-Up, Actors, and Direction Technic. A make-up test pro- 
gram by the American Society of Cinematographers was expanded 
to include color pictures and wide film. A new series of powders 
and greases was developed which photograph exactly as they appear 
to the eye. 69 A leading comedy actor reviewed some of his ex- 
periences in making his first talking picture which was first produced 
as a silent picture. Greater ingenuity was required in introducing 
the sound but at least 50 per cent more laughs were stated to have 
been added. 70 By studying each spoken word of the English ver- 
sion of the picture Lummox, a director so directed a German speak- 
ing cast that their voices were adapted to the lip action of the pro- 
duction. Voices were made to appear to come off the screen when 
expressions could not be made to fit a lip movement. 71 

Trick Work and Special Process Photography. According to Stull 72 
most of the well-known trick effects of the silent picture, such as 
the fade-out, fade-in, lap dissolve, and double exposure, have been 
worked out for sound-on-disk and sound-on-film methods. The de- 
tails of these problems were solved by the cameramen during actual 
pressure of production. Hutchins 73 dealt mathematically with the 
problem of dimensional analysis as an aid to miniature cinematog- 
raphy and showed how, by the application of simple physical laws, 
illusions may be produced which appear real even to the trained mind. 

Coissac 74 described equipment for making animated drawings and 
an elaborately designed machine printer for making enlargements, 
reduction prints, fades, double exposures, etc. The printer is built 
on a rigid steel support which insures freedom from vibration. Light- 
ning effects may be produced, according to Seeber 75 by photographing 
a white wall upon which zig-zag line figures are intermittently pro- 
jected by flashing arc lamps behind special tin masks. 

Patent protection 76 was granted several applicants who disclosed, 
among others: methods for making anaglyphs, a process for ob- 



82 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. P. E. 

taining composite pictures, a method for the synchronizing of sound 
with animated cartoons, and the production of grotesque motion 
pictures by photographing a checkered screen. 

Sound Recording. Historical summaries 77 of the development 
of the sound film industry have been published by Gaumont and by 
Rider. It is of interest that the first patent for an electrical "pickup" 
was issued to Gaumont. Messter 78 has also reported on his trials 
with synchronization of sound and picture started 30 years ago. 

Production programs for sound pictures continued to expand 
during the fall of 1929 and early part of 1930. European studios 
which were slower than the American studios in adopting sound, 
announced their plans for feature pictures in sound late in 1929. 
One German producer planned an American "invasion" by announc- 
ing the making of English versions of twenty feature pictures. 79 
Bohm and Noack have each made analyses of the situation in Ger- 
many during 1929, the latter reviewing the patent difficulties. 80 

Several French studios have commenced sound productions on a 
large scale, a number of them by the RCA variable area process. 
Societe Gaumont which, until quite recently, recorded on the full 
width of a separate film by the Danish Peterson-Poulson method, 
has adopted fixed density recording in the margin of a separate film. 
This record is printed subsequently on the border of the film bear- 
ing the positive image. 

In its latest large installation at Epinay, the firm Tobis is re- 
ported to have given up the system of employing a camera booth 
for sound taking and, like many American studios, has adopted 
sound-proof housings for their cameras. A fixed central station in 
communication with the different sound stages receives by wire the 
current from the microphone. In the Cinevox process, recording is 
accomplished with a glow lamp, according to a variation of the 
DeForest method. 

Soviet engineers have worked out their own systems of sound 
recording and reproducing for use in the Russian studios and theaters. 
One studio in Leningrad and one in Moscow are reported to be mak- 
ing short subjects. 81 

Great interest was shown in the sound school sponsored by the 
Academy of Motion Picture Arts and Sciences and, with the com- 
pletion of the fifth and sixth sections, more than 900 studio workers 
had taken the course. 82 The lectures presented by various authori- 
ties before this school were assembled and published as a Technical 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 83 

Digest. Plans were announced for an actor's school under the 
supervision of the same organization with the aim of giving actors 
the essential facts to assist them in working naturally before the 
microphone. 83 

During the winter of 1929-30, a few grand opera stars were 
prevailed upon to "star" in sound pictures. In March the first 
screen opera, Pagliacci, was produced, sung entirely in Italian. 84 
A talking newsreel* was introduced during December, 1929, which 
had novelty in that it was made without sound in the field but had 
the sound added later in the form of a reporter's running comments 
on the scenes depicted. 85 The problems and troubles of the news 
cameraman had been increased with the advent of sound, for dex- 
terity, skill, and ingenuity were all necessary in securing good place- 
ment of the microphone. 86 Recent improvements in the design 
of compact equipment have decreased some of these burdens. One 
outfit for complete recording, exclusive of the camera, could be 
packed completely in two cases, weighing 70 pounds. 87 

A general review of the problems of sound recording has been 
published by Eisenberg. 88 Too ready acceptance by studios of 
certain practices of sound recording is unwise, according to Coffman, 89 
as the industry is still in a plastic state and mistakes might easily 
be converted to production traditions. One of his warnings about 
too much mixing has already been justified as it is reported that some 
of the studios have eliminated this position. Maxfield 90 has analyzed 
the problem of acoustic control for talking motion pictures. 

Mechanisms for synchronizing sound film cameras have been de- 
scribed by Friess, 91 one promising type employing a magnetic inter- 
locking device to overcome certain disadvantages of synchronous 
motors. 

The Debrie camera has been fitted with a sound-proof housing 
consisting of a box, containing the motor drive encased under the 
camera, and a cover on a vertical track which may be lowered or 
raised quickly by the movement of a hand lever. All controls are 
accessible from outside the case when it is closed. The merits of 
16 different types of camera silencing housings used in Hollywood 
have been tested by a joint committee representing the producers 
and technicians. 92 Most housings were found to absorb more high 

* A sound motion picture illustrating the talking newsreel was shown during 
presentation of this report through the courtesy of Universal Pictures Corpora- 
tion. N. Y. 



84 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. P. E. 

than low frequencies. Motors should be mounted inside the hous- 
ing but improvements are needed in methods of coupling the motor 
to the camera. 

Descriptions of types of German portable sound recording trucks 
have been published. 93 Portable mixing booths mounted on pneu- 
matic tires are reported to be in use. 94 

Data have been given on the frequency ranges of phonograph 
records showing that reproduction is satisfactory for frequencies 
from 50 to 10,000 per second. 95 Knowles 96 believes that film record- 
ing offers more advantages than disk recording. A synthetic resin 
coated on a heavy paper base offers a light, economical, and unbreak- 
able material for the manufacture of disk records. 97 

Borchardt 98 has dealt with the properties of microphones and Kve- 
leigh" has given an historical review of the development of micro- 
phones. Extreme accuracy is needed in the manufacture of micro- 
phones according to an article describing their construction. 100 
Booms for holding the microphone over the actors have undergone 
material development and several ingenious devices are available 
for handling microphones on the set. 101 The booms are operated 
easily by means of telescoping arms which permit operation over 
comparatively large areas. 

Recording and reproducing lights for variable width sound record 
films have been improved and standardized. A 4 ampere, 5 volt, 
single axial filament in a pear shaped bulb is used for recording as 
well as a 6 ampere, 5 volt double axial filament type. For repro- 
duction, a 7 1 /z ampere, 10 volt single transverse filament is used 
with a cylindrical bulb. The Aeo light for variable density record- 
ing has been improved for effective illumination and life. An opti- 
cal system has replaced the slit. For Grandeur pictures on 70 mm. 
film a new optical system was designed. 

Palmer 102 has published details of a device for printing the footage 
numbers on the sound record while it is being exposed in the camera. 
These numbers correspond with those on the picture negative and 
facilitate matching the two negatives for printing. 

Gaumont 103 has suggested leaving room between the picture and 
the perforations on both sides of a film for two sound records as 
might be required if right and left side microphones and reproducers 
were employed for simulating binaural hearing. The two sound 
tracks might also be used for non-synchronized speech in various 
languages. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 85 

A modification of the Poulson magnetized wire recording method 
uses film base impregnated with colloidal particles of an alloy of 
nickel, cobalt, and iron as the magnetically susceptible recording 
material. The film possesses a slight lavender tint when so treated. 104 
The process can be used for amateur standard reversal film or the 
record can be impressed by induction during making of the positive. 

Another novel recording process is that suggested by Madelar 
by which a groove is recorded on the film support by means of a 
diamond stylus. 105 

Improvements in methods of sound recording have resulted in 
a large number of patents, 106 especially in Great Britain, of which 
the following may be described briefly: a sound record having vary- 
ing dielectric characteristics which vary the condenser assembly 
capacity; in recording by means of the Kerr cell, a means for con- 
trolling the light reaching the sensitized surface is provided so that 
it will be restricted to wave-lengths substantially equally affected 
by the cell; the use of a tapered quartz glass, connected to the light 
source of the last element of an optical system, to make "direct im- 
pingement" of the sound influenced beam of light on the sensitized 
support; the enclosure of a camera for sound recording within a 
chamber which is a vacuum or which contains a rarefied atmosphere. 

C. Laboratory Practice 

Production demands necessitated expansion of several Hollywood 
laboratories. 107 Germany has about twenty-five film processing 
laboratories with a combined capacity of approximately two million 
meters of positive film monthly. 108 There are approximately 150 
laboratories for film development in the United States, but the bulk 
of the film is being processed in about 5 per cent of these laboratories. 
According to Hubbard 109 there are six different types of negatives 
which the processing laboratory is required to handle, as necessitated 
by disk, and sound-on-film methods. A summary is given of modern 
versus older methods of processing. 

Machine development has been adopted universally in this country, 
chiefly as a result of the introduction of sound pictures. A Los 
Angeles firm has designed new small tanks and a relatively inex- 
pensive machine. The tanks are arranged horizontally one above 
the other and are about 50 feet long with a drying compartment 
placed above the tanks. Several rolls of film may be processed 
simultaneously. 



86 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. B. 

Inspection projectors in processing laboratories have not as yet 
been fitted with sound testing equipment but the need for such 
installations is becoming apparent. 

Equipment. Rack and reel methods are still in use in the proc- 
essing plants in Australia, of which there are about twenty. A 
more modern laboratory under technical control is being constructed 
to be ready about June 1st. 

Conklin described a densitometer constructed from a Martens 
photometer. 110 A compact developing tank for motion picture 
film consists of special reels around which the film is wound and 
a vertical "ring cylinder" composed of two concentric vertical cylin- 
ders. 111 Wolter described a small metal cylinder for use in develop- 
ing test exposure strips on location. 112 Patent protection 113 was 
granted on devices for automatic inspection of motion picture film 
during processing, means for handling wet film on sprockets, dry- 
ing equipment, development of picture area and sound track (on 
the same film) separately, and improvements in apparatus for the 
development of film by ammonia gas. 

Photographic Chemicals and Solutions. Much attention has been 
given the composition and properties of the photographic solutions 
used for film development in recent years, particularly since the 
general adoption of sound and color pictures. Developer charac- 
teristics are continually changing and a test suggested by Dundon, 
Brown, and Capstaff 114 is of interest, therefore, for it offers a rapid 
means for determining the degree of exhaustion of a developer. A 
two-solution developing procedure, whereby overexposed negatives 
are immersed in a 5 per cent carbonate solution following develop- 
ment, has been suggested by Forstmann and Lux 115 as a means of 
avoiding blocked highlights. Hamer 116 concluded that the use 
of a desensitizer in the form of a preliminary bath is preferable to 
adding it to the developer. 

Fine grain developer formulas for negative development as recom- 
mended by three manufacturers have been discussed by Heering. 117 
A symposium on fixation was conducted by the Royal Photographic 
Society during 1929, papers being presented by Renwick and by 
Baines. 118 The use of a solution of mercuric chloride and potassium 
bromide was shown by Crab tree and Ross 119 to be capable of de- 
tecting 0.05 milligram of sodium thiosulfate (crystal) in motion pic- 
ture film. 

Printing Machines and Methods. Printing machinery is being 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 87 

redesigned rapidly for better quality and more rapid production of 
sound-on-film prints. One manufacturer of printing equipment 
has brought out a single operation printer, and another manufacturer 
is reported to be working on a new model. A new combination 
printing device has been described by Goff 120 which permits both 
optical and continuous printing as well as trick work. It is adaptable 
either to 16 mm. or to 35 mm. film, has a curved gate, a variable 
aperture plate, and the pressure plate is recessed and blackened. 
The Debrie "Matipo" printer was remodeled to adapt it for print- 
ing sound and picture records simultaneously. 121 A new continuous 
printer designed by Lawley is available on the British market. A 
novel feature is that only one tooth of the driving sprocket is in con- 
tact with the film while it passes the exposure aperture. The light 
intensity is magnetically controlled and the printing speed is 90 
feet per minute. 122 Wolter 123 has described a German reduction 
printer in which a violet filter is employed between the light source 
and the 35 mm. film. A sensitometric device known as a "gammeter" 
permits the correct printing exposure for a given negative to be 
found by visual inspection. 124 

One of several problems connected with the reproduction of sound 
has been the proper control of sound level in the theater. Much 
use and some abuse of fader control have resulted from efforts to 
correct for volume variations resulting from recording sound at dif- 
ferent levels and which were not entirely smoothed out by re-record- 
ing. One studio has devised a "squeeze track" for the purpose of 
adjusting differences in sound level. This consists in blocking out 
part of the sound track by exposing it before development to a nega- 
tive consisting of a black line of varying width from zero to the 
full track width. The positive sound track thus becomes a record 
of varying width contained between two black lines filling up the 
remaining space of the track on each side of the track itself which 
is in the center of the space. 

Patents related to printing processes 125 disclosed, among others, 
the following methods: (a) a means of printing two rows of pictures 
on the same face of a film by printing, first, from every alternate 
frame of a negative and, subsequently, printing from the remaining 
frames; (b) synchronization of a positive film and a gramophone 
by printing markings between the pictures which bear a relation- 
ship to divisions on a counter geared with the gramophone; and 
(c) the use of an illuminating system for rapid printing which com- 



88 PROGRESS IN MOTION PICTURE INDUSTRY [J. s. M. p. E. 

prises an extended light source and a quartz block having curved 
sides which, by internal reflection, concentrate the light on a single 
printing point. 

Editing and Splicing. A patch made of film support, 0.003 inch 
thick, was proposed by Crab tree and Ives 126 as a uniform and satis- 
factory method of blocking out splices on sound film. Equipment 
for cutting has been developed on a basis of the needs experienced 
for sound pictures and many of the make-shift devices are giving way 
to commercial products embodying the necessary features for hand- 
ling sound films. Three designs of "Moviolas" are available for 
sound film editing: (a) a sound picture synchronizer for use with 
records on separate films, (b) a disk reproducer, and (c) an apparatus 
for use when sound and picture are on the same film. In the last 
named device, the film movement is continuous; a rotary shutter 
turns inside a cylindrical lamp housing around which the film passes. 127 

Richardson 128 has described a reduced speed motor driven re- 
winder devised by Slagle and Seckel which rewinds at 60 to 90 feet 
per minute. An automatic rewinding device described by Bngel- 
mann 129 in 1928, but not mentioned in previous reports, is of interest 
since the reels lie in a horizontal position. More recently the same 
author has given details of an expanding case for film rolls permitting 
quick removal or replacement. 130 Patent protection has been re- 
quested for a method of editing pictures and sound records, the 
latter being recorded magnetically on a steel wire. 131 Several other 
patents are recorded which relate to improvements in splicing ap- 
paratus. 132 

Titles. With the expanding use of sound film, the necessity for 
titles and titling machines has diminished considerably, although 
for silent releases and for non-theatrical films, titles still find an im- 
portant application. A double titling machine made in Germany 
uses vapor arc lamps and has a capacity of 8000 meters per eight 
hours. 133 Another German device for title making employs a pro- 
jection lamp with a 235 mm. triple condenser for illumination of 
transparent titles. 134 Three patents were issued pertaining to meth- 
ods of preparing title copy for photographing. 135 

After Treatment, Cleaning, Reclaiming, and Storage. A compre- 
hensive discourse was published by Wiegleb 136 on methods of sulfide 
toning which included a review of all articles and patents with refer- 
ences. The chemistry of many selenium compounds and their 
suitability for toning purposes was treated by Sedlaczek. 137 Direc- 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 89 

tions for the use of a dye mordanting formula containing copper 
sulfocyanide were published by Namias. 138 

Sound record prints may be lubricated satisfactorily, according 
to Crabtree, Sandvik, and Ives, 139 by applying a thin coating of 
a solution of paraffin wax in carbon tetrachloride along the edges of 
the film in the perforation area. Film will have a minimum tendency 
to accumulate scratches, dirt, and finger marks, which in turn cause 
ground noise, if edge waxed and buffed after applying a 1 per cent 
solution of cantol wax to the entire emulsion surface. A descrip- 
tion has been published of a film cleaning and treating machine 
which processes 2000 meters of film per hour. 140 

Several processes 141 for film preservation have been exploited 
for which various claims are stated, such as increasing the flexi- 
bility of the film, reducing its tendency to become scratched or buck- 
led, and generally increasing its useful life. Another process is 
particularly recommended for revivifying old films by a method of 
cleaning, brushing, and resurfacing with a chemical treatment to 
eliminate scratches and abrasions. No technical details have been 
published on the chemicals employed. 

One patent of three issued, dealing with cleaning and condition- 
ing processes, describes a method for the treatment of a sound record 
to eliminate "parasitic noise" during reproduction. 142 

As a result of a serious studio fire in the East and a laboratory fire 
on the West Coast during 1929, a great deal of pressure was brought 
to bear on all laboratories to increase their safeguards for fire preven- 
tion. Even before the two fires, however, a committee of representa- 
tives from all laboratories was appointed by Mr. Will Hays to work 
with the National Board of Fire Underwriters to revise the code of 
recommended practice for laboratory requirements. This committee 
has not completed its investigation but is expected to report within 
the next few months. 

The characteristics of nitrocellulose films which may undergo 
flameless combustion at 150C. have been discussed by a well-known 
Federal chemist. 143 Contact with an electric lamp, a heated steam 
coil, a hot wire, or a burning cigarette may ignite such film. Direc- 
tions for the construction of storage vaults for safe storage of this 
material have been published by Brown. 144 A German film safe is 
composed of a series of sliding drawers which may be stacked on top 
of each other and side by side in sections. 145 Additional containers 
for film reels have been patented. 146 



90 PROGRESS IN MOTION PICTURE- INDUSTRY [j. S. M. p. E. 

II. DISTRIBUTION 

Impending adoption of wide film introduces problems for the 
film exchanges, since the larger reels will require larger shipping 
cans and will cost more to ship because of their increased weight. 
An average reel of 70 mm. film weighs 34 pounds and rewinding is a 
man-sized job, requiring care to prevent cinching or tearing of the 
film. 147 

Some idea of the extent of the distribution of ordinary and sound 
prints may be gained from a statement that one of the large pro- 
ducers delivers on an average 155 sound prints compared with 75 
silent prints. Some "star" pictures may run as high as 280 prints. 
The life of an average sound print is 50 to 75 days; that of a silent 
print 90 to 120 days. 148 

A summary of the packing regulations for shipment of film over 

the German governmental railways has been printed. 149 



III. EXHIBITION 

A. General Projection Equipment 

Projectors and Projection. Fox and Richardson 150 have com- 
mented on the projection equipment used for showing 70 mm. film. 
The projector is built more sturdily than older projectors and is 
equipped with a rotating shutter between the light source and the 
film aperture. Maintenance of uniform screen illumination is 
found to be a delicate job at the Roxy where 150 amperes are 
required for the long throw. 151 

An attachment weighing less than 100 pounds has been announced 
for installation on a universal projector base for the showing of a 
film 56 mm. wide, giving a picture ratio of 1 : 2 for projection on screens 
24 feet wide. 152 

A new model Simplex projector, 153 as well as a new assembly for 
older models, was announced in 1929 which incorporates as a special 
feature a rear shutter between the lamp house and the gate. The 
shutter blades are set at a slight angle to create a current of air on 
the gate which is claimed to lower the temperature of the gate 
considerably, to reduce to a minimum the tendency for film buckle, 
and to lower the general fire hazard. Some other features of the 
new model as claimed are easy and rapid change-over from disk to 
sound-on-film, and means for maintaining accurate focus and center- 
ing of the picture. 154 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 91 

Hardy 165 applied the results of a consideration of the conserva- 
tion of energy principle to a discussion of the optics of motion pic- 
ture projectors. Jahn 156 has given interesting data on transformers 
for use with motion picture projectors. A cue meter, consisting of a 
dial attached by a flexible shaft to the shutter shaft on the projec- 
tor, has found practical use and eliminates the need of a long written 
cue sheet. The dial is graduated in feet and is traversed by two 
hands, geared ten to one. 167 Descriptions have been given by 
Lassally 158 of two Berlin theater projection rooms, in one of which 
are installed two non-intermittent projectors. A projector is avail- 
able for projection of Ozophane film which is 0.02 mm. thick. It 
employs a claw pull-down movement and 750 runs were made suc- 
cessfully at a speed of 25 frames per second. 159 

Improvements in pressure plates, claw pull-downs, change-over 
devices, automatic rewinds on the projector, take-up fittings, sprock- 
ets, etc., comprise the essential features of many patents related to 
projection mechanisms. 160 

Sound Picture Reproduction. During the winter of 1929-30, 
sound motion pictures became such an integral and vital part of 
regular theater exhibition programs that their discussion is included 
at this point under general rather than special projection equipment, 
as in past reports. The problem of equipping many thousands of 
theaters for sound reproduction during the comparatively short 
period of a year and a half was a serious and gigantic task both from 
the engineering as well as the economic standpoint. The economic 
problem, according to Franklin, 161 has been a particularly serious 
one for the small exhibitor, for, while the large houses could elimi- 
nate their symphony orchestras and introduce a saving, the small 
house had only a small investment in its orchestra in comparison 
with the cost of installation of reproduction equipment. A lower- 
ing of costs on such equipment alleviated this situation to a certain 
extent. In the meantime, many small exhibitors installed inferior 
low-priced equipment with a resulting lowering of the quality of 
sound reproduction and an inevitable falling-off of box office receipts. 
On the other hand, the steady improvement in sound reproduction 
quality noted in the better equipped theaters stimulated public 
appreciation and, according to a report by Hays, resulted during 
1929 in an increased attendance of 15 per cent or 15,000,000 persons 
per week in the United States. 162 

The advent of the sound picture apparently offered the producers 



92 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. B. 

a plausible excuse for the removal of concert orchestras which many 
of them believed had been appreciated only by an aesthetic minority. 
Surprisingly few complaints from theater goers and no noticeable loss 
of revenue apparently substantiated this opinion. 

Schools for theater projectionists have been established to ac- 
quaint them with the handling of sound equipment and elaborate 
servicing staffs have been formed for the assistance of the theater. 
Numerous practical articles have been written on analysis of sound 
reproduction troubles, such as care of equipment, location of electri- 
cal supply generators relative to the loud speakers, causes of hum 
sounds in reproducers, acoustic nature of draperies and seats in the 
auditorium, etc, 163 

A survey of the literature indicates that considerable attention 
has been paid to the problem of theater acoustics during the early 
months of 1930 as the importance of this problem was fully realized. 
Of interest to the theater patron is Marrisson's 164 method for esti- 
mating by ear, frequencies from approximately 50 to 4000 cycles. 
Norris 165 has described an electrical instrument called an "acoustim- 
eter" for measuring sound intensities. 

Sound picture projection apparatus is in active use on trans- 
Atlantic liners, in a Chicago hotel dining room, and even in rail- 
way cars. A successful showing on a Union Pacific trans-continental 
train was arranged during the fall of 1929. 166 A Delaware corpora- 
tion has been formed to promote a fleet of specially designed rail- 
way coaches as the first unit of a projected nation-wide system of 
mobile sound theaters to present pictures in small villages. 167 The 
first theater for the exclusive showing of sound newsreels opened 
early in November, 1929, running a continuous show from 10:00 
A.M. to midnight. 168 

A description has been given of the Tobis projection equipment 
which is used in Germany and France. 169 The sound record is of 
variable density type. Loud speakers are mounted in sets of six, 
on each side of the screen. Five of each set are of the electro-static 
and one of the electro-dynamic type. Various projectors available 
in Germany have been described by Fischer 170 and by Pander. 171 

The adoption of a standard projection aperture for sound-on-film 
prints, of 0.600 by 0.800 inch is of importance as noted previously 
in this report. 39 It was proposed by a joint committee of technicians 
and engineers and represents a forward step toward better screening 
of sound pictures. Microphone installations connected with the 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 93 

loud speakers on the stage have been made available for theater 
managers' offices to permit the manager to give personal announce- 
ments about coming programs, sport events, and elections, as well as 
to assist in the prevention of panics in case of fire. 172 

Several articles have been written on that important subject of 
volume control, so vital to the interest of the theater patron. 173 
A special fader installation operated from the orchestra floor of a 
New York theater has proven an effective means of controlling 
sound volume during the showing of the picture, RwRita. 174 The 
proper location of horns and other types of loud speakers is still 
somewhat of an open question. 175 Analyses of types of loud speakers 
have been made by Vogt, 176 and by Blattner and Bostwick. 177 An 
audible frequency selector has been designed for use in the projec- 
tion room which it is claimed permits the projectionist to accentuate, 
attenuate, or eliminate certain frequencies delivered to the ampli- 
fier. 178 

Details have been published on the technical characteristics of 
all the sound reproducing equipment on the French market. 179 The 
only French process which is complete from the taking to the pro- 
duction end is that of Gaumont. Their projector, known as "I/ Ideal 
Sonore," uses a selenium cell illuminated with a 220 watt lamp, 
for sound-on-film reproduction, and is also equipped with a syn- 
chronized disk for records. A special amplifier for the selenium 
cell is provided, located on the projector, and a three stage audio 
amplifier delivering a telephonic power of 150 watts which may be 
located anywhere desired. 

.Dunoyer 180 has reviewed the characteristics of photo-electric cells 
with especial mention of a cell manufactured in France. Nason 181 
has dealt with the design of audio frequency apparatus in a series 
of three articles. Electro-magnetic pickups were discussed by 
Grouse, 182 and Hatschek 183 treated the subject of amplifiers and 
hook-ups to minimize distortion. 

Additional installations have been made in theaters to make sound 
pictures audible for deaf patrons. The equipment consists of a 
network tapping the sound energy in the reproducing system with 
a separate amplifier capable of supplying sufficient power for thirty 
headsets. 184 

The number of available types of turntable reproducers continued 
to increase monthly for each one of which certain meritorious claims 
were advanced. 185 



94 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. E. 

Various improvements in sound reproduction equipment have 
been patented 186 relating to synchronization of disk records with 
pictures, constant speed control of film projector mechanisms, ten- 
sion regulators, etc. Two other patents are interesting because 
of their novelty: (a) Broadcast sounds are synchronized with cine- 
matographic films, illustrating the subject broadcast and projected 
in one or more theaters, by the aid of duplicate strips, on which 
the speech and music are marked so the projectionist, by means of 
his copy strip and speed regulator, can adjust the projector to syn- 
chronize with the received sounds. 187 (b) Motion pictures have 
been reproduced on metal film, and projected by reflected light. 
The sound track is produced either photographically, mechani- 
cally, or magnetically. 188 

Projector Lenses, Shutters, and Light Sources. Improved efficiency 
has been claimed for a projector shutter which consists of three cut- 
out disks on separate shafts. 189 The center of the lens is uncovered 
first and covered last. A number of patents 190 have been issued 
both here and abroad on improvements in lenses and shutters. 

The introduction of sound and color pictures has resulted in in- 
creased amperage for screen illumination with greater accompanying 
trouble from heat on the gate aperture. This excess heat causes 
the film to buckle and increases the fire hazard. To overcome these 
difficulties the manufacturers of the Simplex projector designed a 
rear shutter assembly for use on existing projectors which, it is 
claimed, effectively reduces the heat incident on the gate from a 
170 ampere high intensity arc more than 65 per cent. 153 

A 500 watt lamp for general studio illumination and a projector 
incandescent lamp have been announced in France which are silvered 
on one-half of the bulb interior as a means of increasing their effi- 
ciency. 191 Naumann 192 studied the light distribution over the face 
of a condensing mirror in relation to each part of the picture area. 
In another paper the same author gave results of tests with a novel 
photographic set-up which indicated that the mirror arc under av- 
erage working conditions gives unequal illumination of the center 
and edge of the film aperture. 193 

A unique generator known as the Rosenberg cross-field generator 
is being marketed by an Austrian firm located in Vienna (Fig. 3). 
An arc, such as that in a projector, may be connected directly to 
the generator and the voltage and current are self regulating. Two 
of the four commutator brushes are short circuited. When the 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 



95 



outer circuit is closed, a magnetic field and an armature field result in 
the same direction, but opposed, the former increasing slowly, the 
latter rapidly. The resulting field strength then becomes weaker, 
the potential at the brushes grows less, and the current is lowered. 

A new high intensity arc was designed which is especially suitable 
for the projection of wide film. 194 Joy and Downes 1 * 5 presented 
a useful paper at the Toronto meeting on the characteristics of high 
intensity arcs. Only three patents dealing with projector light 
sources have been noted since the last report. 196 

Fire Protection. Ignition tests were conducted by the Los Angeles 
Bureau of Standards and Research on several different motion pic- 




\ 



\ 



FIG. 3. Diagram (left) of Rosenberg cross-field generator and curve (right) 
showing effect on voltage of increasing the amperage. Reproduced by courtesy 
of Dr. P. Schrott, Vienna, Austria. 

ture films; the lowest ignition temperature found was 250F. 197 
Cabourn 198 reviewed various methods for minimizing fire risks dur- 
ing projection. A non-inflammable substitute for nitrate film is 
considered the real solution. Alteration of projector design so that 
the shutter would operate between the lamp house and the gate is 
strongly advocated for reducing the heat reaching the film. This 
scheme is incorporated in the new projector design previously noted 
under the section on Projectors and Projection. In case of a film fire, 
one type of fire extinguisher releases a gas from outlets in the pro- 
jector which smothers the fire. 199 

The importance of the question of fire prevention is indicated by 



96 PROGRESS IN MOTION PICTURE INDUSTRY [j. s. M. p. E. 

the number of patents which have been issued dealing with auto- 
matic means for closing apertures, operating dousers, disconnecting 
electrical lighting circuits, prevention of burning of the film in case 
of breakage, etc. 200 

B. Special Projection Equipment 

Portable Projectors. A new sound-on-film portable projector equip- 
ment made by RCA was announced in October, 1929. 201 The pro- 
jector and sound reproducer is housed in a metal cabinet 24 inches 
square and 12 inches wide mounted on four telescopic legs. The 
magazines are attached to the outside of the housing. The amplifier 
is housed in a separate metal cabinet and permits volume control 
in graded steps of 2 TU from zero to maximum volume. Accommo- 
dation is made in the amplifier for a second projector to permit smooth 
change-over. The speaker is an electro-dynamic moving coil cone 
type. The equipment takes about an hour to assemble. 

Further details have been made available on the portable sound 
equipment supplied by Western Electric. 202 The delivery and take- 
up reels are included on the same shaft inside the projector case. 
A 60 foot throw is possible giving a picture 7 feet by 8 feet in 
size. 

Dahlgreen 203 has given data on a German projector of the suit- 
case type as "Kinobox C." Light is reflected from a mirror set 
at an angle of 45 degrees to the film plane and the rotating shutter 
is positioned between the light source and the film. Descriptions 
have also been published of two other portable projectors of Ger- 
man manufacture, the "Grawor" and the "Matador." 204 A window 
display projector uses 35 mm. film and projects pictures 9 inches by 
12 inches, which remain 7 to 12 seconds on the screen. 205 The Kohm 
advertising projector uses a loop of 16 mm. film, 120 meters long. 206 

In the "Speico" automatic projector, the lamp house, motor drive, 
gate, and lens system are mounted on a horizontal box holding the 
film which feeds from the center and rewinds from the outside of 
the roll. The film edges rest on a number of threaded metal cylin- 
ders arranged radially around the center of the magazine. One of 
these cylinders is connected to each of the extremities of a vertical 
drum for guiding the film from its entrance to its exit from the case 
and to keep a constant length of film outside of it. Upper and lower 
sprockets, ventilation of the film, and the lantern, and a humidify- 
ing device are features of this projector. 207 

I 



July/ 1930] PROGRESS IN MOTION PICTURE INDUSTRY 97 

A few patents have been issued concerned with improvements 
in projector design, methods of utilizing an endless strip of film, 
etc. 208 

Stereoscopic Projection. Earth 209 prepared a review of the sys- 
tems for the production of stereoscopic motion pictures. A device 
for which claims of relief effects were made was demonstrated in 
Hollywood in November. 210 A standard camera and regular film 
stock were used. Another apparatus was demonstrated also on the 
Coast which was patented in 1915 but was perfected mechanically 
only recently. Bi-lensed optical systems are avoided and individual 
viewing frames are said to be unnecessary. Alternate frames are 
photographed from laterally varying positions (angles), the optical 
center of the lens representing the pivotal point. A train of motor- 
driven gears and cams are built into the tripod head. 211 Only two 
patents were noted dealing with devices for obtaining relief effects. 212 

Non-intermittent Projection. In one type of continuous projec- 
tor supplied by an English firm, a ring of lenses rotates in the place 
usually occupied by the rotary shutter. The speed of rotation of 
each lens corresponds to the rate of travel of the film in the gate 
in such a way that each lens is maintained central with its appropriate 
film picture which is thus projected stationary on the screen. 213 

Another non-intermittent type of projector, also manufactured 
in England, was designed so that the film passes upward through 
the gate which accommodates two picture frames. Moving parallel 
with the film and at equal speed is a continuous band of 14 lenses 
arranged in a channel shaped like the letter "D" the flat side of which 
is nearest the gate. Two images, or one complete image with parts 
of two others, are available which, by means of a master lens and 
an ordinary projector lens, are superimposed on the screen. 214 

A continuous projector designed by a Frenchman, M. R. Hue, 
has several novel aspects to recommend its consideration. Film 
is passed on a curved track in the form of a part cylinder before a 
light aperture somewhat higher than that of a single frame. An 
image is projected onto a mirror in the center of the cylinder and 
set at an angle of 45 degrees to the light path. The mirror turns 
at a speed one-half that of the moving film through a slight arc and 
then returns to the original position while a shutter cuts off the 
light momentarily. A stationary image is projected on a screen 
placed at right angles to the original light source. Means are pro- 
vided for framing a single picture on the screen. 



98 PROGRESS IN MOTION PICTURE INDUSTRY [J. S. M. p. E. 

A projector with continuous movement and using unperf orated 
film on Ozaphane stock has been demonstrated in Paris. 215 

The interest shown in design of non-intermittent projector devices 
is indicated by the comparatively large number of patents which 
have been taken out on such equipment. 216 

C. Theater Design and Installation 

Screens. Larger screens are generally being installed for standard 
projection, the size most used in the larger houses on the Coast being 
18 feet by 24 feet. Certain producers are planning installation of 
large screens for the showing of wide films. 

A mechanical device operated from the projection booth permits 
masking the screen to any size needed in three seconds. 217 A sound 
screen is constructed entirely of asbestos. 218 Another sound screen 
is made with a glass beaded surface. 219 The screen is fire-proof, 
may be washed, and rolled up. A screen used by the Film Guild 
Cinema is stated to be made up with laminated gold and other 
metals as well as pigments. Arc amperage is said to be lowered 50 
per cent by its use. 220 

Some of the ideas patented relating to projection screens are the 
following: a screen surface comprising agglomerated microscopic 
spheroidal particles of a considerable range in size; screens having 
mica dust or finely ground quartz on their display surface, a day- 
light screen which includes the use of a rayon screen before the 
regular screen, the former stopping the light falling angularly on 
the screen ; a screen comprising a thin sheet of water dropped through 
space from a suitable container, etc. 221 

Theater Illumination. Paints which fluoresce strongly under ultra- 
violet radiation have been used to paint costumes and scenery for 
the production of startling effects. 222 Types of batten spotlights 
available in Great Britain for stage illumination have been de- 
scribed. 223 Electrically interlocked mo*tors form the connecting 
link between the control board and the grouped pre-set modulators 
in different theater stage lighting circuits. 224 

A new stage and theater lighting system known as Colorama 
has been developed by the General Electric Company. It consists 
of a scheme of cones and flutes with lamps and color media so arranged 
as to give changing and overlapping color and shadow effects. Glass 
filters are used instead of gelatin. 225 






July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 99 

Theater Acoustics and Construction. Considerable attention has 
been given the theater acoustics problem during the year of 1929. 
One firm has made an acoustical analysis of over 1500 theaters and 
made recommendations for treatment of the auditoriums. A lower- 
ing of the accepted optimum reverberation time as a function of 
volume was reported. 226 Theaters with square auditoriums were 
found in general to have better acoustic properties than long narrow 
theaters. Kellogg 227 stated that the trend will be toward very 
"dead" theaters in the future with the recording and reproduction 
arranged to adjust such variables as reverberation and loudness. 
According to Friend, 228 seats should be made of materials which 
absorb nearly as much sound as a person. Hair felt and other 
soft materials which reduce the reverberation have a high selective 
absorption for frequencies above 1000 and a masking of the audi- 
bility of high tones results. 229 

Eyring 230 has shown that the common method of calculating 
reverberation times is incorrect in some cases. Since theaters are 
effectively corrected to optimum amount of sound absorption, how- 
ever, calculations with the old formftla will result in correct adjust- 
ment in most instances. For sound stage treatment the new method 
is of importance, as it shows that a very dead set may be obtained 
by the use of less absorbing material than the older formula would 
indicate. 

The effect of distortion on speech sounds during transmission 
was discussed by Steinberg. 231 The treatment considered only the 
effect on articulation and not at all the tonal quality of the sound. 
Knudsen 232 examined the factors affecting articulation in an audi- 
torium after first discussing the characteristics of speech and hearing. 

Lindahl 233 discussed several of the special acoustical problems of 
theaters from small 200 seat houses to large 5000 seat houses. Hat- 
schek 234 analyzed data on building acoustics of motion picture 
theaters. Curved surfaces and domes should be avoided, according 
to Schiffe. 235 Carter 236 recommended lining the ceiling and walls 
with compressed cane fiber board, to reduce reverberation, and 
leaving air spaces in the walls. The proper adaptation of ceiling 
design with relation to the rest of the auditorium will provide all 
the audience beyond two-fifths the distance from front to back with 
equally clear reception. 237 

Scenery painted on brilliantly colored paper and impregnated 
against fire may be illuminated either from the front or back and 



100 PROGRESS IN MOTION PICTURE INDUSTRY [J. s. M. P. E. 

costs less to manufacture. 238 A seating system for theaters con- 
sists of an automatic switch equipped to light a lamp at both the 
end of the row and on a chart in the foyer indicating row and seat 
number. 239 A box having an illuminated ground glass over which 
a continuous length of "score" film (photographically prepared) 
is passed eliminates the necessity for a director of a theater orchestra 
and insures easy synchronization with the projected picture. 240 

IV. APPLICATIONS OF MOTION PICTURES 

A. Education, Business, and Legal Records 

Sound motion pictures began to be used for non-theatrical pur- 
poses during 1929. The Hotchkiss School in" Lakeville, Conn., 
was reported according to Lewin, 241 to be the first school to have 
sound reproduction facilities installed. He also reported that an 
experimental program of sound pictures was planned for a Newark, 
N. J., public school in April or May, 1930. A film entitled Adminis- 
tration Departments of the Federal Government was selected for pro- 
jection. This film included voice and picture records of the Presi- 
dent of the United States. Lewin gave a list of 18 industrial 
and educational sound pictures. A description was published of a 
sound film on vocational guidance made by Kitson of Columbia 
University. 242 Announcement of plans was made of the U. S. De- 
partment of Agriculture for recording such events as the National 
Dairy Show in sound. 243 

A sound newsreel was made of the wireless reception of the news 
of Admiral Byrd's flight over the South Pole. 244 More than 1000 
feet of motion pictures were reported to have been made of the polar 
regions during this flight. 

The first transcontinental use of a sound motion picture as a sub- 
stitute for the presence of the actual person is stated to be the address 
made by Hon. R. L. Wilbur, U. S. Secretary of the Interior, in May, 
1929, at the Muybridge Celebration at Stanford University. It 
was shown with portable equipment. 245 A more extensive appli- 
cation of this public address idea was made in January, 1930, when 
a corporation president spoke in eleven different cities on the same 
evening at the annual president's dinner, through the medium of 
the sound picture. 246 

Future students in universities may be able to see as well as hear 
some of the world's leading scientists which should serve to enhance 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 101 

their interest in the investigations of such men.* Sound films were 
made of lecture demonstrations by Sir Oliver Lodge, Sir Ernest 
Rutherford, Sir William Bragg, well-known English scientists, and 
of Dr. Irving Langmuir of the Research Staff of the General Electric 
Company. 247 

A series of sound motion pictures relating to business conditions 
has been planned by Harvard University on the subjects Regions 
of the United States, and Commerce and Industry. 246 

Confessions of the defendants in burglary and murder trials** 
were recorded in Philadelphia as a part of an experimental investi- 
gation on the value of the sound motion picture in criminal court 
practice. 249 It was reported that a bureau is to be established for 
making sound pictures of prisoners so as to have records of their 
voices, gestures, and mannerisms. A similar bureau has been es- 
tablished in Paris by the Surete Generale. 250 

The cultural course, "Introduction to the Photoplay," established 
in 1928 at the University of Southern California, has been continued 
and has also been adopted by Stanford University and the University 
of Iowa. 251 Courses on technical and scientific cinematography 
were begun at the Vienna Technische Hochschule under Dr. P. 
Schrott and a three year course has been established in Berlin. 252 
Santini 253 stated that there are over 5000 projectors being used for 
showing educational films in Italian schools. A resume of the uses 
made of classroom films as an aid to teaching has been published 
by McClusky. 254 According to Walters, 255 increased interest, as 
well as a better understanding of processes, resulted from showing 
industrial films as a part of the work of chemistry classes in an Okla- 
homa high school. Thirty- two new films for classroom use have 
been released since October, 1929, by a corporation organized for 
the production of such films. A total of over ninety films have 
been .prepared. 

A motion picture conference held in New York between leaders 
of the industry and civic, educational, religious, and social service 
organizations, resulted in a better understanding of the relation- 
ship between the industry and the public. 256 Educators have 

* A sound motion picture illustrating the educational application of sound 
pictures was shown during presentation of this report through the courtesy of 
General Electric Company, Schenectady, N. Y. 

** A sound motion picture of a murderer's confession was shown during pre- 
sentation of this report through the courtesy of the Fox Film Corporation, N. Y. 



102 PROGRESS IN MOTION PICTURE INDUSTRY [j. s. M. P. E. 

urged that the best photoplays should be preserved and revised for 
visual education after they have served their entertainment pur- 
poses. 267 A Dutch society for the preservation of motion picture 
records of the history of the Netherlands was organized in 1919 
and has collected more than 1000 films during the decade. 258 

B. Medical Films, Radiography, and Photomicrography 

Included in a group of motion pictures shown at the 1929 fall 
convention of the American College of Surgeons were four sound 
pictures, three of which were recorded addresses accompanying 
diagrammatic pictures, while the fourth represented an obstetrical 
operation accompanied by dialog. 259 The operation was performed 
by Dr. DeLee, well-known Chicago obstetrician, and the dialog 
was synchronized with the film by a crew of Fox cameramen.* Dr. 
DeLee has an elaborate laboratory for motion picture photography 
in the Lying-in Hospital in Chicago. It is also equipped with an 
animation department. 260 

Sound films have been made for the Los Angeles County Health 
Department by Hearst-Metrotone cameramen to encourage greater 
interest in public health. 261 Motion pictures of living cells of body 
tissues were made by Rosenberger, working with Carrel at the 
Rockefeller Institute, and shown at the Thirteenth International 
Physiologists Congress in 1929. Studies requiring days of obser- 
vation were shown to an audience in half an hour. 262 Roon 263 pre- 
dicts that voice recording of wills, testimony at trials, property 
sales, etc., will make records of greater value and accuracy than 
written records. Fifteen medical films have been prepared in a 
program under the auspices of the American College of Surgeons, 
the Motion Picture Producers and Distributors of America, and 
the Eastman Kodak Company. Subjects made during 1929 deal 
with acute appendicitis, obstetrics, vestibular function, and de- 
velopment of the rabbit's ovum. The last named picture was 
made by Dr. W. H. Lewis of the Carnegie Institute of Embryolgy 
in Baltimore and represents a beautiful example of photomicrog- 
raphy. 

Umbehr 264 has published an historical survey of attempts made 
to produce X-ray motion pictures. A method used by Ruggles is 

* A portion of this sound motion picture of Dr. DeLee's operation was shown 
during presentation of this report through the courtesy of Dr. J. B. DeLee, 
Chicago, 111., and the Fox Film Corporation, N. Y. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 



103 



considered by another writer to be very promising. The X-ray 
tube is turned on and off every twenty-fifth of a second in place of 
using a shutter. 265 Studies of movements of the heart may be made 
by roentgenographing the heart through a series of parallel slits in 
a lead screen upon a film moving slowly past the slits. 266 Rosen- 
berger 267 published a brief description of a method for attach- 
ing the Eyemo camera to a microscope. An automatic micro- 
cinematographic apparatus mounted on a heavy rigid support has 
been described by Coissac. 268 Storch of Vienna made ultra-rapid 




FIG. 4. Camera and photomicrograph used by Storch of Vienna for 
ultra-rapid motion analysis studies of microorganisms. Reproduced by 
courtesy of Dr. P. Schrott, Vienna, Austria. 



motion analysis studies of microorganisms using an Askania high 
frequency camera. To reduce vibration effect, the camera was 
attached horizontally to the wall but the microscope may be used 
either in a horizontal or vertical position. (Fig. 4.) Exposures 
mostly over 100 per second were used, focussing was done with a 
green filter interposed, and the arc current reduced to 5 amperes 
so as to minimize heating effects on the delicate organisms. 

Canti of London filmed the growth of normal, and of cancer cells. 269 
Francois-Franck and collaborators made motion picture studies of 



104 PROGRESS IN MOTION PICTURE INDUSTRY [j. S. M. p. E. 

white blood cells in vitro and of the embryonic development of the 
sea urchin. 270 

C. Telephotography and Television 

The general public may deposit ordinary messages in postal boxes 
conveniently located in three leading French cities for transmission 
by telephotography as part of a service begun in France during 
1929. 271 

The industry is alive to the possibilities of television and further 
progress has been made which, though rather slow, is encouraging. 
Three producers have included reservation of television rights in 
their contracts. 272 A demonstration of the RCA Kerr cell principle 
apparatus was given at Procter's 58th Street Theater in New York 
in January. Jenkins 273 gave a summary of progress by his method 
at the last meeting of the Society held in October, 1929. Accord- 
ing to his estimates about 20,000 amateurs are receiving radio movies 
which are broadcast from station W3XK, Washington. Other 
new television stations are WENR, Chicago, operated by the Great 
Lakes Broadcasting Company, 274 and W2XCR, Jersey City, and 
W2XCD, Passaic. The last two named stations synchronize radio 
with the pictures and, though the images were said to be hazy, the 
lip movements are stated to be discernible with the sound. 275 A 
painted rectangle was transmitted by short waves in February from 
station W2XAF, Schnectady, to Sydney, Australia, and re-broad- 
cast back again by station VK2ME in an elapsed time of one-eighth 
second. 276 

A new cathode ray type of receiver giving a picture 4 inches by 
5 inches has been described by Zworykin. 277 The method eliminates 
the high frequency motor previously necessary for synchronization, 
together with its power amplifier. No moving parts are used. A 
fluorescent screen aids the eye's persistance of vision and makes 
possible a reduction of the number of images per second without 
noticeable flicker. The transmitter is a modified motion picture 
projector with means for horizontal scanning. 

The selection of standards for radio television has been discussed, 
including picture proportions, number of scanning elements, number 
of pictures per second, scanning method and direction, and phase 
of current. 278 

In the Telefunken system of television being developed in Ger- 
many, a combination of a mirror wheel for illuminating the subject 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 



105 



and a photo-electric cell are used for sending, and a Kerr cell, together 
with a rotating mirror wheel, for receiving. 279 A French patent 
covering one phase of this process has been issued. 

D. General Recording 

A camera capable of taking 40,000 pictures per second by means 
of a drum having 180 mirrors, revolving 225 times per second, was 
exhibited in 1929 at a Scientific Con- 
gress in Tokyo. The camera was de- 
signed by the Institute for Physical 
Research of the University of Tokyo. 280 
Cranz and Schardin 281 described a 
method for photographing a series of 
pictures of rapid action on a stationary 
piece of film, the time between suc- 
cessive pictures being variable from 
0. 1 to 0.000003 second. Lawrence and 
Dunning of the University of California 
have been studying the characteristics 
of the high voltage spark by means of 
a camera which has a shutter speed 
equivalent to the taking of 250,000 
pictures per second. A 20,000 volt 
spark lasting 0.00001 second was 
found to be nearly 50 per cent hotter 
than the sun. 

Cinematographic methods were used 
to time the high speed Schneider Cup 
airplane races held at Calshot, Eng- 
land, in the fall of 1929. A motion 
picture camera made pictures of the 
plane as it crossed the start and finish 
line and also recorded simultaneously 
the face of two calibrated Veeder 
counters which were actuated by a 
tuning fork vibrating 10 times per 
second. 282 (Fig. 5.) A machine gun 
motion picture camera makes 300 
exposures per second, and, by means 
of a network of lines covering the image, it is possible to 




FIG. 5. Print from timing 
record of world's high speed air- 
plane flight at Calshot, England, 
September, 1929. Note Veeder 
counter numbers reproduced 
along left side of film strip. Re- 
produced by courtesy of the 
Royal Air Force. 



106 PROGRESS IN MOTION PICTURE INDUSTRY [j. s. M. P. E. 

make a number of calculations of value to the designer of air- 
planes. 283 

A company has been formed in Paris to publish on cinematographic 
films, reproductions, page by page, of manuscripts, rare books, etc., 
with the necessary illustrations. Application for a patent covering 
this principle has been made. 284 A device known as a photographic 
accelerometer was attached as a fifth wheel to the running board 
of an automobile and, by means of suitable disks and a motion pic- 
ture camera, records were made of the distance travelled per second. 285 

A patent for an apparatus for making motion pictures of a moving 
object (such as an oil well rope, to detect wear) has been granted. 286 

V. COLOR CINEMATOGRAPHY 

As noted earlier in this report the use of motion pictures in color 
has continued to expand and a number of new processes have ap- 
peared, although technical descriptions of them are rather meager. 
The new Technicolor laboratory in Hollywood has been completed 
and is stated to have a daily capacity of 47,000 feet of finished color 
film. Daily rushes are to be developed and printed in color on one 
side only, whereas double coated film has been used in the past. 287 
An estimate has been made that 15 per cent of all pictures made in 
1930 will be in color. 

The first German all-color sound picture, The Nun of Heiligen- 
worthy produced by Detofa of Berlin is scheduled for release in May, 
1930. 288 Color sequences by the Horst three-color process are to 
be included in releases by the British Instructional Films Ltd. in 
the spring of 1930. 289 Newsreels made by a new color process were 
released by Pathe in March, 1930. The process is claimed to be 
equally as rapid in production as black and white prints and avoids 
the use of filters and prisms. Pictures of the New Orleans Mardi 
Gras floats were made and shown the following week in New York. 290 
A recording photometer or color analyzer has been designed for the 
measurement of color values in sets, thus permitting more accurate 
control of illumination. 291 

A general summary of the principles and processes of color photog- 
raphy has been published by Matthews 292 which includes an ex- 
tensive bibliography of all books and articles published on the sub- 
ject between 1925 and 1930. 

In the Herault Trichrome process, three-color component nega- 
tives are exposed in rapid succession by means of a rotating sector 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 



107 



wheel; for the positive, a similar projecting device is used. 293 Ac- 
cording to the scheme devised by a Boston inventor, prints from 
a color component negative exposed with the aid of a rotating sec- 
tor wheel, are projected onto a special metal screen built up of 
four separate sections, each one being displaced slightly in front of 
the other and, except for the bottom one, perforated with holes. 
The outer screen is blue, the second yellow, the third red, and the 
base screen azure blue. Stereoscopic effects and undistorted side 
views are claimed. 294 




RAVCOL Optical System 




FIG. 6. Diagram of optical system used in the Raycol two-color additive 
process, and positive print showing disposition of component images. Re- 
produced by courtesy of Kinemato graph Weekly, London, England, and 
Dr. W. Clark, Harrow, England. 

Patents on three-color additive processes 295 described improve- 
ments in methods for utilizing color screens, objectives for super- 
posing multiple images during projection, and a four-color method 
for exposing the four images on one frame with suitable projection 
facilities for registration on the screen. 

A company is reported to have been organized in Switzerland 
for the exploitation of a color motion picture process using film 



108 PROGRESS IN MOTION PICTURE INDUSTRY [j. s. M. p. E. 

coated on a lenticulated support. Patents related to lenticulated 
films 296 are concerned chiefly with methods of printing such films 
and with equipment for embossing the film support. 

Naumann 297 has given a description of the illuminating equip- 
ment and other apparatus used by the Busch two-color additive 
process for medical cinematography. The film runs horizontally 
through the camera gate and the images, one-half standard size, 
are registered lengthwise along the film, one above the other, in 
such a way as to occupy one frame. 

In the Raycol two-color additive process demonstrated in England, 
light enters the camera and is divided into two parts by means of 
a beam splitter. (Fig. 6.) It is then caused, by a system of rhom- 
boids, to form two images one-quarter normal size in opposite quar- 
ters of the frame on standard size film, one through an orange filter, 
and the other through a blue-green filter. A twin lens projector 
with the appropriate filters over the lens superimposes the two posi- 
tive images on the screen. 298 

Several patents 299 disclosing features of two-color additive proc- 
esses have appeared, concerned with exposure and projector mechan- 
ism, the production of stereoscopic effects, and the positioning of 
the image pairs on the film, and other features. 

Arc lights equipped with "silencers" are stated to be in use again 
for the production of Technicolor features, of which one hundred 
are scheduled for 1930. Cameras for this process are being manu- 
factured at a cost of $14,000 and in April, 1930, about fifty cameras 
were stated to be available. 300 

A new film is reported to have been adopted for the Multicolor 
process which permits exposures on a black and white base. 301 In 
the Colorcraft process, although a beam splitter optical system, was 
originally employed, early in 1930 the color separation negatives 
were being made by running two negative films, emulsion to emulsion, 
through the camera. Specially hardened double coated positive 
stock was utilized in making the positive records on which the color 
records were produced as dye images. Vague descriptions have 
been published of two other processes known as Photocolor and Harris 
color, respectively. The former purports to be a two-color process 
using dyed images on double coated film; 302 the latter is stated to 
be a three-color process using a single emulsion film for printing. 303 

The Sirius color process announced in Germany in 1929 pro- 
duces the red and green exposures on alternate frames by means 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 109 

of a beam splitter and the prints are made on opposite sides of a 
double coated film, both sides being dyed simultaneously in the 
production of the color image. 304 The process was demonstrated in 
London early in 1930. 

A considerable number of patents for subtractive color motion 
picture processes appeared during the past six months. 306 

VI. AMATEUR CINEMATOGRAPHY 

A . General Equipment and Uses 

Corns tock 306 reviewed the progress in amateur cinematography 
from the period of the popularity of 28 mm. equipment to the present 
time. Thirteen makes of amateur standard cameras were available 
as well as several types of 9.5 mm. cameras. An automobile was 
equipped for demonstrating amateur motion picture equipment in 
the rural sections of England. 307 

A new apparatus for synchronizing 16 mm. film with disk records 
was described by Bristol. 308 A special printing device was designed 
to make prints either from 35 mm. or 16 mm. negatives, omitting 
every third frame. These shortened films may then be projected 
at 16 pictures per second, thus avoiding the noise made by amateur 
projectors when speeded up to 24 pictures per second. The turn- 
table synchronizer drives the projector synchronizer at twice its 
own speed. 

Amateur Cameras. Several new models of amateur cameras ap- 
peared during the latter part of 1929 and the early months of 1930. 
The Filmo 70D incorporates seven speeds, three lenses on a turret, 
and a special view finder as features of its design. 309 A slow motion 
mechanism is incorporated in the Cine Ansco which is fitted with an 
//3.5 lens. 310 Two new models of the Cine Nizo cameras were 
announced, both being fitted for four speeds and running off about 
35 feet of film with one winding of the clock spring. 311 Three models 
of the Bolex Swiss camera are available, which have as a feature 
an exposure meter housed within the camera and an audible footage 
meter. Earlier models were fitted with //3.5 lenses but a more 
recent model has an //2.5 lens. 312 

The Kodel camera exposes four pictures on each frame of 16 mm. 
film by a mechanism which introduces an alternate horizontal and 
vertical movement of the film. The pictures are projected by a 
similar movement on a rear projector screen, the images being reflec- 



110 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. p. E. 

ted from a shielded mirror onto the screen. 313 McKay 314 described 
methods of producing distortion effects by exposing motion pictures 
through ophthalmic prisms and an auxiliary lens. 

Most of the patents issued on camera mechanisms are related to 
designs of claw pull-downs, spring drives, and types of film maga- 
zines. 316 

Projectors. A combination projector turntable using a 16 inch 
disk recorder was announced for home talking pictures. 316 A Ger- 




FIG. 7. Motion pictures being projected by an amateur projector on an 
airplane during a transcontinental flight. Reproduced by courtesy of the 
Illustrated London News. 

man firm is also supplying a turntable and magnetic pickup suitable 
for attaching to any 16 mm. projector. 317 A non-intermittent ama- 
teur projector employs a 12 sided prism in a cylindrical mount which 
revolves between the aperture and the objective. 318 

A passenger airplane flying from Columbus, Ohio, to Los Angeles 
was equipped to show motion pictures on 16 mm. film en route. 
(Fig. 7.) The projector was operated with dry cells and a daylight 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 111 

screen was used. 319 Richman 320 briefly mentioned an amateur sound 
film process developed by Tager, a Moscow engineer, which incor- 
porated sound and pictures on the film. 

A new model Victor 16 mm. projector is equipped with a fan for 
cooling the rheostat, and a half -hour show is possible as an 800 foot 
reel may be utilized. 321 Two models of the Ampro projector are 
available, one of which is said to give a very bright screen since a 
250 watt 20 volt lamp is used. The design of each is compact, 
all controls being mounted on one plate at the base. 322 The Bolex, 
Model C projector is air cooled and uses a 100 watt lamp capable 
of giving a picture 5 feet by 8 feet in size. It weighs six pounds. 
Stills may be projected. 

Patents 323 related to projector mechanisms provide for projec- 
tion of stills, reversal of the film, and details of claws, reels, etc. 

Accessories. A new Ross "Xpres" lens of aperture //1. 9 is made in 
1 , 1 Y 2 , and 3 inch focal lengths for amateur cine enthusiasts. 324 Tests 
made on the extreme aperture Dallmeyer lens listed as //0.99 show 
good definition but rather small depth of focus. 325 An automatic 
panoraming device has been made available. 326 An improved 
rewind and splicing equipment represent a useful addition to the 
amateur's splicing table. 327 A combined exposure meter, distance 
gauge, and view finder has been described, which may be geared to 
the camera. 328 Only three patents deal with accessory devices. 329 

Scenarios. Useful suggestions on set construction were published 
by Hugon 330 and on miniature building by Waller. 331 

Films and Film Processing. The bulk of amateur motion pic- 
tures exposed on 16 mm. film are being developed to a positive by 
one of several reversal processes. A few firms began to supply negative 
film but most of this film was withdrawn from the market late in 
1929. An unbreakable film was described which consists of strips 
of 16 mm. film, 4 3 / 4 inches long, sealed between thin pieces of steel 
which have holes cut through for the pictures and the film perfora- 
tions. These strips are projected by stacking them in a projector 
magazine where an electro-magnet picks up the top strip which is 
then moved intermittently past a horizontal aperture. A mirror 
deflects the image along a horizontal axis onto a translucent screen. 
Test runs of 15,000 passages through the projector are claimed to 
show no wear on the film. 332 

Several articles have been published giving formulas and manipu- 
lative details for developing film by reversal. 333 



112 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. p. K. 

B. Amateur Color Processes 

Only two patents 334 were noted dealing with color processes; one 
describes a color filter holder for projectors, and the other describes 
the use of a curved exposure gate in processes utilizing lenticulated 
film. 

VII. STATISTICS, PUBLICATIONS, AND NEW BOOKS 

A survey made early in 1930 by the secretaries of the thirty- two 
Film Boards of Trade of the Motion Picture Producers and Dis- 
tributors of America revealed that there were 22,624 motion picture 
theaters operating in the United States. 335 New York had 1233 
theaters, Illinois had 1286, and Ohio had 1247. About half the 
total number were wired for sound pictures. There were reported 
to be 57,743 theaters in the world as shown by a census taken by the 
Motion Picture Division of the U. S. Department of Commerce. 336 
With the increased total for the United States shown in the Board 
of Trade's report, the world total would be 59,867. 

A United States Department of Commerce report 337 stated that 
2200 foreign theaters were wired for sound pictures by the end of 
1929, distributed as follows: Europe 1500, Far East 400, Latin 
America 250, other places 50. There were 256 patents issued in 
Great Britain during 1929 relating to motion picture processes, 52 
of which dealt with color processes and 57 with sound processes. 
Patents on motion pictures granted in Great Britain for the last 
thirty years outnumbered those in any other field. 338 About $28,000,- 
000 were paid into the Treasury for entertainment tax by the theaters 
of Great Britain. 339 

About 115,000,000 persons attended theaters weekly in the United 
States during 1929, an increase of 15 per cent over 1928. It was 
estimated that a half billion dollars were invested in sound motion 
picture development during 1928 and 1929. 340 Exports of film in- 
creased in 1929 over 1928, 282,000,000 feet being shipped out in 
1929 as compared with 222,000,000 feet in 1928. Of the total for 
1929, 8,400,000 feet represented negative film and 273,000,000 feet 
was positive film. 341 There were 145 feature pictures imported in 
1929 as against 193 in 1928, the decrease being a result of the use of 
sound pictures only a few of which were being made abroad. 342 

There were approximately 1400 show houses in Australia which 
is a country having slightly larger area than the United States but 
having only 6,000,000 people. Two-thirds of the population are con- 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 113 

centrated near the six capitol cities. About 600,000 feet of positive 
prints entered the country weekly. The vaudeville theaters were 
being wired during the winter of 1929-1930 for sound pictures. 

Pictures made in studios of American companies represented 85 
per cent of all film entertainment in 1929, although United States 
producers made less than half of the world's feature product. 843 
The yearly payroll of Hollywood producers reached $100,000,000, 
averaging $2,000,000 weekly. 344 

A comprehensive series of reports was issued by the Motion Pic- 
ture Division of the U. S. Department of Commerce on conditions 
in the motion picture industry in Italy, Roumania, France, Persia, 
and Germany. 345 North also reviewed the high-lights of the Euro- 
pean situation for the year 1929 giving data on production, distribu- 
tion, theaters, and legislation. 346 

Over 230 types of synchronous and non-synchronous sound equip- 
ment were installed in United States theaters in 1929. 847 

PUBLICATIONS AND NEW BOOKS 

Valuable summaries of developments in the motion picture industry were 
published during 1929 in the Encyclopedia Britannica. The subjects treated 
and the authors are as follows: History T. Ramsaye; Production J. L. 
Lasky; Sets C. Gibbons; Acting M. Sills; Direction C. B. DeMille; 
Make-Up L. Chancy; Technology C. E. K. Mees. 

A section of the 1930 Supplement of the New International Encyclopedia 
deals with motion pictures and was prepared by R. Watts. In the article on 
Photography in this same publication, G. E. Matthews reviewed the growth of 
motion pictures from 1914 to 1929. 

This Society passed a milestone in its progress when the Transactions issued 
quarterly for several years were replaced by a monthly JOURNAL, beginning 
January, 1930. Other new publications started during the past year are Pro- 
jection Engineering, Electronics, Journal of the Acoustical Society of America, and 
Cinematography. New books which have appeared are as follows: 

1. Technical Digest, Academy Motion Picture Arts and Sciences, Hollywood, 
Calif., 1930. A compilation of published lectures given as part of a school on 
sound fundamentals. 

2. Year Book of Motion Pictures, Film Daily, N. Y., 1930, 12th Ed. 

3. Kinematograph Year Book, Kinematograph Publications Ltd., London, 
1930, 17th Ed. 

4. Encyclopedia on Sound Motion Pictures, Cameron Publishing Co., Man- 
hattan Beach, Brooklyn, N. Y., 1930. 

5. Photographic Emulsions, by E. J. Wall, American Photographic Publish- 
ing Co., Boston, Mass., 1929, 256 pages. 

6. See and Hear, by W. Hays, Mot. Pict. Producers and Distributors of 
America, Inc., New York, 1930, 63 pages. 



114 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. P. E. 

7. On Film Technique, by V. I. Pudovkin, Trans, from Russian by I. Mon- 
tagu, Gollancz, Ltd., London, 1930, 204 pages. 

8. Sound Projection, by R. Miehling, Mancall Publishing Co., New York, 
1929, 528 pages. 

9. Photo-electric Cells, by N. R. Campbell and Dorothy Ritchie, I. Pitman 
& Sons, New York, 1929. 

10. Sound Pictures and Trouble Shooters Manual, by J. R. Cameron and J. F. 
Rider, Cameron Publishing Co., Manhattan Beach, Brooklyn, N. Y., 1930. 

11. Sound, edited by A. James, Exhibitor's Daily Review and Motion Pictures 
Today, New York, 1930. 

12. Sensitometry, Photographic Photometry, and Spectrography (Die Sensito- 
metrie, Photo graphische Photometrie und Spektrographie), by J. M. Eder, W. 
Knappe, Halle, 1929. This is Part 4 of Vol. Ill of the Ausfuhrliches Handbuch 
der Photographic. 

13. Photo -chemistry and Photographic Chemicals (Photochemie und photo- 
graphische Chemikalienkunde) , by A. Coehn, G. Jung, J. Daimer, W. Knappe, 
Halle, 1929. This is Vol. Ill of Handbuch der Wissenschaftlichen und Ange- 
wandte Photographic, edited by A. Hay. 

. 14. Photo-chemistry and Photographic Chemistry (Photochemie und Photo- 
graphische Chemie), by W. Noddack and E. Lehmann, Union Deutsche Verlags., 
Berlin, 1929. This is Vol. I, Part 1, of Handbuch der Photographie, edited by 
H. W. Vogel. 

15. Manufacture and Testing of Photographic Materials (Fabrikation und 
Prufung der Photo graphischen Materialien) , by W. Nauck and E. Lehmann, 
Union Deutsche Verlags., Berlin, 1929. This is Vol. 1, Part 2, of Handbuch der 
Photographie, edited by H. W. Vogel. 

16. Production and Testing of Light Sensitive Films, Light Sources (Erzeugung 
und Prufung Lichtempfindlicher Schichten, Lichtquellen) , by M. Andresen, F. 
Formstecher, W. Heyne, R. Jahr, H. Lux, A. Trumm. This is Vol. IV of Hand- 
buch der Wissenschaftlichen und Angewandte Photographie, edited by A. Hay. 

17. Electric Transmission of Pictures and the Telehor (Das Elektrische Fernsehen 
und das Telehor), by D. von Mihaly, M. Krayn, Berlin, 1926, 196 pages. 

18. Television, by H. H. Sheldon and E. N. Griesewood, D. Van Nostrand 
Co., New York, 1929, 194 pages. 

19. Radio Movies, Radiovision, Television, by C. F. Jenkins, National Capital 
Press, Inc., Washington, D. C., 1929, 143 pages. 

REFERENCES 

1 RICHARDSON, F. H.: Ex. Herald-World, 98, Sec. 2 (March 15, 1930), p. 49. 

2 RAYTON, W. B.: J. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 50. 

3 HOWEU,, A. S., AND DUBRAY, J. A.: J. Soc. Mot. Pict. Eng., 14 (Jan., 1930), 
p. 59. 

4 JONES, L. A.: /. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 32. 

5 GREGORY, C. L.: /. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 27. 

6 Mot. Pict. News, 41 (Feb. 15, 1930), p. 20. 

7 J. Soc. Chem. Ind., 43 (Aug. 2, 1929), p. 771. 

8 Reports Mot. Pict. Div., U. S. Dept. Commerce (Oct. 23, 1929). 

9 Brit. Pats. 310,540; 313,829; 318,250. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 115 

10 Ger. Pat. 483,892. 

11 Fr. Pat. 650,345; Ger. Pats. 480,352; 482,103; U. S. Pat. 1,719,711. 
* 12 Ger. Pat. 480,729. 

13 SCHMIDT, R.: Filmtechnik, 5 (Apr. 27, 1929), p. 194. 

14 JONES, L. A., AND SANDVIK, O.: J. Soc. Mot. Pict. Eng., 14 (Feb., 1930), 
p. 180. 

16 CONKUN, O. E.: /. Opt. Soc. Amer., 17 (Dec., 1928), p. 463. 

16 U. S. Pat. 1,717,815; Brit. Pat. 317,459; Fr. Pat. 653,040; Australian 
Pat. 15,873; Ger. Pat. 483,807. 

17 CARSON, W. H.: /. Soc. Mot. Pict. Eng., 14 (Feb., 1930), p. 209. 

18 U. S. Pat. 1,738,054; Brit. Pat. 321,540; Fr. Pats. 33,191; 33,487; 33,724 
(add. 635,828); 652,735; 654,750; Ger. Pats. 476,041; 483,894. 

19 Ex. Herald-World, 98, Sect. 1 (Jan. 18, 1930), p. 35. 

20 Los Angeles Times, Cream Sheet Section (Mar. 23, 1930). 

21 Ex. Herald-World, 99 (Apr. 5, 1930), p. 11. 

22 Filmtechnik, 5 (Nov. 9, 1929), p. 465. 

23 SCHULTZ, R.: Filmtechnik, 5 (Nov. 9, 1929), p. 467. 

24 HENLEY, A. T.: Kinemat. Weekly, 152 (Oct. 3, 1929), p. 61. 

25 Film Daily, 51 (Feb. 9, 1930), p. 11. 

26 Bioscope, 80 (Aug. 21, 1927), p. 37; also Kinemat. Weekly, 151 (Sept. 19, 
1929), p. 43. 

27 UMBEHR, H.: Filmtechnik, 5 (Nov. 9, 1929), p. 470. 

28 DANASHEW, A.: International Phot., 1 (Dec., 1929), p. 7. 

29 EMMERMANN, C., AND SEEBER, G.: Filmtechnik, 5 (Aug. 31, 1929), p. 381. 

30 NOULET, L.: Photo-Revue, 41 (July 1, 1929), p. 195. 

31 Ex. Daily Review and Mot. Pict. Today, 26 (Nov. 30, 1929), p. 12. 

32 U. S. Pat. 1,729,520; Ger. Pat. 475,981; Fr. Pat. 650,957. 

33 STULL, W.: Amer. Cinemat., 10 (Feb., 1930), p. 9. 

34 EVELEIGH, L.: Bioscope, 80 (Aug. 7, 1929), p. iii. 
^NATEBUS, F.: Filmtechnik, 5 (Nov. 23, 1929), p. 496. 

36 FEAR, R. G.: Internal. Phot., 1 (Oct., 1929), p. 41. 

37 Amer. Cinemat., 10 (Jan., 1930), p. 11. 

38 LUBITSCH, E.: Amer. Cinemat., 10 (Nov., 1929), p. 5. 

39 COWAN, L.: /. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 108; also Report of 
the Standards and Nomenclature Committee, ibid., p. 131. 

40 OWEN, R.: Internal. Phot., 1 (Oct., 1929), p. 14; also Mot. Pict., 5 (Oct., 
1929), p. 7. 

41 LiEBERENZ, P. L.: Filmtechnik, 5 (Oct. 12, 1929), p. 436. 

42 SEEBER, G.: Filmtechnik, 5 (Nov. 23, 1929), p. 497. 

43 SMACK, J. C.: /. Soc. Mot. Pict. Eng., 14 (Apr., 1930), p. 384. 

44 HENRI-ROBERT, J.: Bull. soc. franc, phot., 16 (May, 1929), p. 141. 
45 JoNSON, G.: Internal. Phot., 1 (Dec., 1929), p. 39. 

46 Internal. Phot., 2 (Feb., 1930), p. 16. 

47 LICHTENSTEIN, W.: Filmtechnik, 5 (June 8, 1929), p. 248. 

48 MOHR, H.: Amer. Cinemat., 10 (Nov., 1929), p. 34. 

49 U. S. Pats. Re. 17,443 of 1,355,543; 1,719,205; 1,720,744; 1,730,045; 
Canad. Pats. 290,803; 293,037; Brit. Pats. 311,411; 314,001; 314,991; 315,360; 
316,255; 316,302; 317,489; 319,406; 320,378; 320,379; 321,683; Ger. Pats. 



116 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. P. E. 

471,058; 473,948; 474,055; 477,807; 478,904; 480,588; 481,165; 483,736; 
483,743; 483,805; 484,625; 485,236; Fr. Pats. 633,405 (2nd add. 32,870); 
633,180 (add. 33,466); 614,421 (add. 32,830); 650,949; 651,512; 652,214; 
652,298; 652,642; 657,082. 

Kinotechnik, 11 (Mar. 5, 1929), p. 124. 

61 Ger. Pats. 474,650; 485,413. 

52 Filmtechnik, 5 (May 11, 1929), p. 214. 

53 EMMERMANN, C. : Phot. Chronik, 36 (May 28, 1929), p. 205. 

54 McCov, J. L.: /. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 357. 

55 Fr. Pat. 651,580. 

56 EVELEIGH, L.: Bioscope, 79 (June 19, 1929), p. ix; ibid., 80 (July 24, 31, 
1929), pp. iii and iii. 

67 Kinotechnik, 11 (June 20, 1929), p. 333. 

58 Licht Bild Buhne, 22 (May 18, 1929), p. 20. 

59 GORDON, N. T.: J. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 332. 

60 RICHARDSON, E.: Internal. Phot., 1 (Dec., 1929), p. 22. 

61 Amer. Cinemat., 10 (Mar., 1930), p. 22. 

62 BUCK, O. K., AND ALBERT, J. C.: /. Soc. Mot. Pict. Eng., 14 (Apr., 1930), 
p. 399. 

63 Filmtechnik, 5 (Mar. 16 and Aug. 3, 1929), pp. 109 and 369; also Kino- 
technik, 11 (May 20 and Sept. 5, 1929), pp. 274 and 469. 

64 PATZELT, F.: Kinotechnik, 11 (Aug. 20 and Oct. 5, 1929), pp. 434 and 513; 
REEB, O.: ibid., 11 (Dec. 5, 1929), p. 635. 

65 CLERC, L. P.: Sci. Ind. Phot., 9 (July, 1929), p. 75. 

66 ABADIE, M.: Sci. Ind. Phot., 1, 2nd Series (Apr., 1930), p. 158. 
67 BENFORD, F.: J. Soc. Mot. Pict. Eng., 14 (Apr., 1930), p. 404. 

68 Amer. Cinemat., 10 (Sept., 1929), p. 22. 

69 Amer. Cinemat., 10 (Nov., 1929), p. 13. 

70 LLOYD, H.: Hollywood, 18 (Nov., 1929), p. 14. 

71 Ex. Herald-World, 97 (Nov. 2, 1929), p. 36; Mot. Pict. News, 40 (Oct. 19, 
1929), p. 26. 

72 STULL, W.: /. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 318. 

73 HUTCHINS, G. F.: /. Soc. Mot. Pict. Eng., 14 (Apr., 1930), p. 377. 

74 COISSAC, G. M.: Cineopse, 12 (Jan., 1930), p. 47. 

75 SEEBER, G., Filmtechnik, 5 (June 22, 1929), p. 261. 

76 U. S. Pats. Re. 17,330 of 1,589,731; 1,729,617; Ger. Pats. 474,649; 475,091; 
Brit. Pats. 318,838; 321,436; Fr. Pats. 644,518; 657,029. 

77 GAUMONT, L.: Bull. soc. franc, phot., 16 (Mar., 1929), p. 62; also RIDER, 
J. F.: Mot. Pict. News, 39 (Mar. 2, 1929), p. 627. 

78 MESSTER, O.: Kinotechnik, 11 (Nov. 20, 1929), p. 592. 

79 Ex. Herald-World, 98 (Mar. 8, 1930), p. 18. 

80 Filmtechnik, 5 (Apr. 27, 1929), pp. 171 and 173. 

81 Amer. Cinemat., 10 (Mar., 1930), p. 18. 

82 Bull. Acad. Mot. Pict. Arts and Sciences, No. 30 (Apr. 18, 1930), p. 5. 

83 Bull. Acad. Mot. Pict. Arts and Sciences, No. 29 (Feb. 27, 1930), p. 29. 

84 Film Daily, 51 (Mar. 30, 1930), p. 6. 

85 Ex. Herald-World, 97 (Dec. 14, 1930), p. 39. 

86 JONES, H. W.: /. Soc. Mot. Pict. Eng., 14 (Feb., 1930), p. 204. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 117 

87 Amer. Cinemat., 10 (Feb., 1930), p. 29. 

88 EISENBERG, J. G.: Projection Eng., 1 (Nov., 1929), p. 22. 

89 COFFMAN, J. W.: /. Soc. Mot. Pict. Eng., 14 (Feb., 1930), p. 172. 
^MAXFIELD, J. P.: /. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 85. 

91 FRIESS, H.: Filmtechnik, 5 (Aug. 3, 1929), p. 332. 

92 Mot. Pict. News, 41 (Feb. 22, 1930), p. 28. 

93 Filmtechnik, 5 (Sept. 14, 1929), p. 407; also Kinemat. Weekly, 152 (Oct. 
31, 1929), p. 55. 

94 Amer. Cinemat., 10 (Dec., 1929), p. 35. 

95 Filmtechnik, 5 (Oct. 12, 1929), p. 447. 

96 KNOWLES, H. S.: Ex. Herald-World, 97, Sect. 2 (Oct. 26, 1929), p. 43. 

97 Rochester Times-Union, 12 (Jan. 24, 1930). 
^BORCHARDT, C. : Filmtechnik, 5 (Apr. 27, 1929), p. 181. 

99 EVELEIGH, L.: Bioscope, 80 (June 26 and July 3, 1929), pp. iii and vii. 

100 Ex. Herald-World, 96, Sec. 1 (Sept. 28, 1929), p. 36. 

101 Internal. Phot., 1 (Jan., 1930), p. 30. 

102 PALMER, M. W.: /. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 327. 
103 GAUMONT, L.: Bull. soc. franc, phot., 16 (Mar., 1929), p. 59. 
104 SEEBER, G.: Phot. Ind., 27 (Apr. 3, 1929), p. 389. 

105 CRAWFORD, M.: Internal. Phot. Bull. (March, 1930), p. 20. 

106 U. S. Pats. 1,715,863; 1,718,618; 1,719,462; 1,722,088; 1,736,139; Canad. 
Pat. 291,386; Brit. Pats. 310,933; 312,161; 313,536; 314,003; 314,095; 315,562; 
315,754; 315,842; 316,171; 316,484; 317,735; 318,143; 318,508; 319,246; 
319,373; 319,280; 319,913; 320,431; 320,653; 320,872; Fr. Pats. 649,368; 
658,552. 

107 Ex. Herald-World, 97 (Oct. 5, 1929), p. 36; also Internal. Phot., 1 (Feb., 
1930), p. 35. 

IO GRAFMANN, J.: Filmtechnik, 4 (Nov. 10, 1928), p. 437. 

109 Year Book of Motion Pictures, Film Daily, N. Y. (1930), p. 893. 

110 CONKUN, O. E.: Internal. Phot., 1 (Feb., 1930), p. 22. 

111 Phot. Ind., 26 (July 18, 1928), p. 751. 

112 WOLTER, K.: Film fiir Alle, 3 (July, 1929), p. 199. 

113 U. S. Pats. 1,716,441; 1,723,950; 1,726,834; Ger. Pat. 483,895; Fr. Pats. 
649,135; 650,123. 

114 DUNDON, M. L., BROWN, G. H., AND CAPSTAFF, J. G.: /. Soc. Mot. Pict. 
Eng., 14 (April, 1930), p. 389. 

115 FORSTMANN, W., AND Lux, A.: Filmtechnik, 36 (June 25, 1929), p. 244. 

116 HAMER, F. M.: Phot. J., 69 (Nov., 1929), p. 479. 

117 HEERING, W.: Photofreund, 9 (Nov. 5, 1929), p. 416. 
8 Phot. J., 69 (July, 1929), pp. 310 and 314. 

119 CRABTREE, J. L, AND Ross, J. F.: /. Soc. Mot. Pict. Eng., 14 (April, 1930), 
p. 419. 

120 GoFF, D. J.: Amer. Cinemat., 10 (Jan., 1930), p. 201. 

121 COISSAC, G. M.: Cineopse, 12 (Jan., 1930), p. 47. 

122 EVELEIGH, L.: Bioscope, 80 (Aug. 14, 1929), p. iii. 
123 WoLTER, K.: Filmtechnik, 5 (Oct. 26, 1929), p. 453. 

124 HOKE, I. B.: Internal. Phot., 1 (May, 1929), p. 6. 

125 U. S. Pats. 1,718,037; 1,721,202; 1,724,933; 1,725,944; 1,729,867; Brit. 



1 18 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. p. B. 

Pats. 316,623; 318,688; 319,660; Fr. Pats. 640,510; 650,904; 654,253; Ger. 
Pat. 478,616. 

126 CRABTREE, J. I., AND IVES, C. E.: J. Soc. Mot. Pict. Eng., 14 (Mar., 1930), 
p. 349. 

1 27 Amer. Cinemat., 10 (Feb., 1930), p. 33. 

1 28 RICHARDSON, F. H.: Ex. Herald-World, 98, Sect. 2 (Mar. 15, 1930), p. 50. 

129 ENGELMANN, M.: Filmtechnik, 4 (Apr. 14, 1928), p. 140. 

130 Licht Bild Buhne, 22 (July 6, 1929), p. 15. 

131 Brit. Pat. 319,679. 

* 32 U. S. Pats. 1,714,605; 1,716,879; 1,727,349; 1,728,974; 1,729,660; 1,732,- 
755; 1,734,140; 1,734,142; Ger. Pats. 476,204; 476,302; Fr. Pat. 658,395; 
Brit. Pat. 320,058. 

133 Filmtechnik, 4 (June 23, 1928), p. 246. 

* 34 Filmtechnik, 5 (Feb. 16, 1929), p. 69. 

135 Ger. Pats. 473,626; 473,717; 474,402. 

136 WIEGLEB, P.: Brit. J. Phot., 76 (June 14, 21, and 28, 1929), pp. 344, 363, 
and 375. 

137 SEDLACZEK, A.: Brit. J. Phot., 75 (Dec. 28, 1928), p. 784; ibid., 75 (Jan. 4, 
18, and 25, 1929), pp. 4, 29, and 41. 

1 38 NAMIAS, R.: // prog, fot., 35 (1928), pp. 19, 109, and 145. 

139 CRABTREE, J. I., SANDVIK, O., AND IvES, C. E.: J. Soc. Mot. Pict. Eng., 
14 (Mar., 1930), p. 275. 

140 Filmtechnik, 5 (Mar. 16, 1929), p. 110. 

141 Mot. Pict. News, 39 (May 4, 1929), p. 1496; also Film Daily, 51 (Jan. 22, 
1930), p. 1; Mot. Pict. Projectionist, 3 (Feb., 1930), p. 41; and Amer. Phot., 23, 
(Sept., 1929), p. 501. 

142 Brit. Pat. 313,906; U. S. Pat. 1,716,878; Fr. Pat. 653,955. 

143 Mot. Pict. News, 40 (Dec. 28, 1929), p. 22. 

144 BROWN, C. R.: Safety Engineering (Aug., 1929), p. 65. 

145 Licht Bild Buhne, 22 (Apr. 20, 1929), p. 24. 

146 U. S. Pat. 1,726,573; Fr. Pat. 656,470. 

147 RICHARDSON, F. H.: Ex. Herald-World, 98, Sect. 2 (Mar. 15, 1930), p. 49. 

148 Film Daily, 50 (Oct. 11, 1929), p. 1. 

149 Filmtechnik, 5 (May 2, 1929), p. 93. 

150 Fox, D., AND RICHARDSON, F. H.: Ex. Herald-World, 97, Sect. 2 (Sept. 26, 
1929), p. 17. 

151 RICHARDSON, F. H.: Ex. Herald-World, 98, Sect. 2 (Mar. 15, 1930), p. 49. 

152 Mot. Pict. News, 41 (Apr. 5, 1930), p. 75. 

RICHARDSON, F. H.: Ex. Herald-World, 98 (Feb. 22, 1930), p. 41. 

154 GRIFFIN, H.: Amer. Projectionist, 8 (Feb., 1930), p. 4. 

155 HARDY, A. C.: J. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 309. 
156 jAHN, E.: Kinotechnik, 11 (Aug. 5, 1929), p. 395. 

157 McCuLLOCH, R. H.: Mot. Pict. News, 41 (Apr. 5, 1930), p. 88. 
158 LASSALLY, A.: Kinotechnik, 11 (May 20, 1929), p. 262. 

159 Filmtechnik, 5 (Sept. 28, 1929), p. 421; also Cinemat. franc., 10 (Apr. 28, 
1928), p. 45. 

160 U. S. Pats. 1,718,782; 1,725,595; 1,728,670; 1,731,733; 1,733,481; 1,733,- 
830; 1,738,053; Brit. Pats. 314,312; 316,607; 317,283; 318,283; 320,637; 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 119 

321,660; Fr. Pats. 33,496 (add. 529,856); 33,738 (add. 639,380); 643,757; 
651,454; 652,506; 654,168; 654,313; Ger. Pats. 474,056; 481,232; 485,626. 

161 FRANKLIN, H. B.: /. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 302. 

162 Ex. Herald-World, 97 (Dec. 14, 1929), p. 25. 

163 Mot. Pict. News, 39 (Apr. 13, 1929), p. 1174; Ex. Herald-World, 96, Sect. 
2 (July 6, 1929), p. 37; ibid., 98, Sect. 2 (Jan. 18, Feb. 15, Mar. 15, 1930), pp. 
29, 40, and 40; Kinemat. Weekly, 152 (Oct. 24, 1929), p. 61 ; Year Book of Motion 
Pictures, Film Daily, N. Y. (1930), pp. 879 and 985. 

164 MARRISSON, W. A.: Project. Eng., 2 (Mar., 1930), p. 14. 

165 NORRIS, R. F.: Project. Eng., 1 (Sept., 1929), p. 43. 

166 Mot. Pict. News, 40 (Nov. 2, 1929), p. 36. 

167 Mot. Pict. News, 40 (Dec. 14, 1929), p. 20. 

168 Ex. Herald-World, 97 (Nov. 9, 1929), p. 21. 

169 Filmtechnik, 5 (Feb. 2, 1929), p. 50. 

170 FISCHER, F., Filmtechnik, 5 (Aug. 3, 1929), p. 350. 

171 PANDER, H.: Filmtechnik, 5 (Apr. 27, 1929), p. 207. 

172 Canad. Mot. Pict. Digest, 21 (Mar. 22, 1930), p. 5. 

173 Mot. Pict. Projectionist, 2 (Feb., 1929), p. 11; ibid., 2 (Oct., 1929), p. 14. 

174 Mot. Pict. Projectionist, 3 (Feb., 1930), p. 27. 

175 Ex. Herald-World, 97, Sect. 2 (Oct. 26, 1929), p. 50; Mot. Pict. Projectionist, 
2 (Oct. 1929), p. 28; Mot. Pict. News, 40 (Dec., 7, 1929), p. 32. 

m VOGT, H.: Filmtechnik, 5 (Apr. 27, 1929), p. 202. 

177 BLATTNER, D. G., AND BOSTWICK, L. G.: /. Soc. Mot. Pict. Eng., 14 (Feb. 
1930), p. 161. 

178 Mot. Pict. Projectionist, 3 (Feb., 1930), p. 32. 

179 Cinemat. franc., 12 (Nov., 1929), p. 28 et seq. 

180 DUNOYER, L. : Cinemat. franc., 12 (June 22, 1929), p. 1. 

181 NASON, C. H. W.: Project. Eng., 1 (Oct., Nov., Dec., 1929), pp. 22, 26, and 
26. 

182 GROUSE, G. B.: Project. Eng., 1 (Oct., 1929), p. 27. 
183 HATSCHEK, P.: Filmtechnik, 5 (Aug. 3, 1929), p. 353. 

184 Mot. Pict. News, 40 (Sept. 7, 1929), p. 885; Ex. Herald-World, 97, (Dec. 7, 
1929), p. 50; Project. Eng., 2 (Feb., 1930), p. 32. 

185 Mot. Pict. News, 40 (Oct. 5, 1929), pp. 1229 and 1231; ibid. (Nov. 2, 1929), 
p. 54; Mot. Pict. Projectionist, 2 (Sept., 1929), p. 32; Bioscope, 80 (Aug. 7, Sept. 
25, 1929), pp. vii and vii; ibid., 81 (Nov. 13, 1929), p. 21; Kinemat. Weekly, 
148 (June 27, 1929), p. 54; ibid., 149 (July 4, 1929), p. 85; ibid., 150 (Aug. 1 and 
15, 1929), pp. 51 and 69; ibid., 151 (Sept. 12, 1929), p. 75; ibid., 152 (Nov. 7, 
1929), p. 57. 

186 U. S. Pats. 1,723,343; 1,728,304; 1,729,048; 1,729,427; Brit. Pats. 310,476; 
316,320; 317,299; 318,847; 319,197; 319,592; 319,761; 319,791; 321,148; 
321,624; Fr. Pats. 617,111; 650,948; 659,270; Ger. Pats. 481,231; 485,132; 
486,100. 

187 Brit. Pat. 320,881. 

188 Ger. Pat. 485,598. 

189 Mot. Pict. News, 40 (Sept. 7, 1929), p. 876. 

190 U. S. Pats. 1,720,011; 1,734,221; 1,738,445; 1,738,945; Brit. Pats. 315,702; 
316,256; 316,376; 320,601; Ger. Pats. 481,561; 482,080; Fr. Pat. 657,324. 



120 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. P. E. 

191 Sci. Ind. Phot., 2nd Series, 1 (Mar., 1930), p. 118. 
192 NAUMANN, H.: Kinotechnik, 11 (June 20, 1929), p. 311. 
193 NAUMANN, H.: Filmtechnik, 5 (Aug. 31, 1929), p. 389. 

194 Amer. Cinemat., 10 (Feb., 1930), p. 20. 

195 JOY, D. B., AND DOWNES, A. C.: J. Soc. Mot. Pict. Eng., 14 (Mar., 1930), 
p. 291. 

196 U. S. Pat. Re. 17,350 of 1,620,956; Brit. Pats. 313,338; 316,613. 

197 Amer. Projectionist, 7 (Aug. 1929), p. 3. 

198 CABOURN, J. A.: Bioscope, 80 (Sept. 25, 1929), p. ix. 

199 Mot. Pict. Projectionist, 2 (May, 1929), p. 17. 

200 U. S. Pats. 1,718,540; 1,719,377; 1,725,284; 1,725,556; 1,725,574; 1,733,- 
433; 1,737,034; Brit. Pats. 313,272; 313,439; Fr. Pats. 33,271; 33,497; and 
33,737 (add. 631,777); 643,479; 654,743; 658,248; 658,409; 658,794; 658,795; 
Ger. Pats. 481,302; 485,237; 485,238; 486,101. 

201 DANSON, H. L.: Project. Eng., 1 (Nov., 1929), p. 58; also Ex. Herald-World, 
97 (Dec. 21, 1929), p. 45. 

202 WOLF, S. K.: Project. Eng., 2 (Mar., 1930), p. 11. 

203 DAHLGREEN, R.: Filmtechnik, 5 (Oct. 12, 1929), p. 441. 

204 Kinotechnik, 11 (Oct. 5, 1929), p. 525. 

205 Sci. Amer., 141 (July, 1929), p. 66. 

206 Licht Bild Buhne, 22 (Aug. 24, 1929), p. 15. 

207 D'HERBEUMONT, L.: Cineopse, 12 (Jan., 1930), p. 63. 

208 U. S. Pats. 1,714,816; 1,727,900; Brit. Pats. 316,994; 320,817; Fr. Pats. 
33,603 (add. 579,679); 656,703; 657,654; 658,421; Ger. Pats. 485,075; 485,677. 

209 Plastische Bild, Nos. 9 and 10 (Sept.-Oct., 1928), p. 98. 

210 Ex. Daily Review and Mot. Pict. Today, 26 (Nov. 23, 1929), p. 3. 

211 Amer. Cinemat., 10 (Jan., 1930), p. 32. 

212 Brit. Pat. 310,527; Fr. Pat. 652,379. 

213 Kinemat. Weekly, 152 (Oct. 24, 1929), p. 77. 

214 Bioscope, 81 (Nov. 13, 1929), p. xvii. 

215 Bioscope, 81 (Nov. 13, 1929), p. 21. 

216 U. S. Pats. 1,717,044; 1,723,768; 1,731,490; 1,739,422; Brit. Pats. 310,654; 
312,177; 312,645; 313,613; 317,733; 318,276; 318,535; 318,905; 319,284; 
319,302; 319,678; Fr. Pats. 643,277; 650,986; 653,320; 659,562; Ger. Pats. 
474,057; 481,135; 481,162; 481,163; 481,966; 484,054; and 484,053 (add. 
481,162). 

217 Mot. Pict. Projectionist, 2 (May, 1929), p. 38. 

218 Mot. Pict. News, 40 (Dec. 7, 1929), p. 32. 

219 Mot. Pict. News, 40 (Oct. 5, 1929), p. 1229. 

220 Ex. Herald-World, 96, Sect. 2 (Aug. 31, 1929), p. 40. 

221 U. S. Pats. 1,715,381; 1,720,232; 1,734,467; Brit. Pat. 314,719; Fr. 
Pats. 640,033; 650,027; 653,956; Ger. Pat. 474,451. 

222 Fox, D.: Ex. Herald-World, 96, Sect. 2 (July 6, 1929), p. 32. 

223 Bioscope, 81 (Oct. 23, 1929), p. vii. 

224 Mot. Pict. News, 40 (Nov. 2, 1929), p. 58. 

225 Amer. Cinemat., 10 (Mar., 1930), p. 15. 

226 WOLF, S. K.: Acad. Tech. Digest, Hollywood, Cal., 1930, p. 109; also 
J. Soc. Mot. Pict. Eng., 14 (Feb., 1930), p. 151. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 121 

KELLOGG, E. W.: J. Soc. Mot. Pict. Eng., 14 (Jan., 1930), p. 90. 

FRIEND, W. K.: Ex. Herald-World, 98, Sect. 2 (Feb. 15, 1930), p. 9. 

22 WENTE, E. C.: Project. Eng., 1 (Sept., 1929), p. 19. 

230 EYRING, C. F,: /. Acoustical Soc. Amer., 1 (Jan., 1930), p. 217. 

'"STEINBERG, J. C.: J. Acoustical Soc. Amer., 1 (Oct., 1929), p. 121. 

" KNUDSEN, V. O.: Acad. Tech. Digest, Hollywood, Cat. (1930), pp. 18 and 45. 

233 LINDAHL, R. L.: Ex. Herald-World, 96, Sect. 2 (Aug. 3, 1929), p. 41; ibid., 
96, Sect. 2 (Aug. 31, 1929), p. 31; ibid., 98, Sect. 2 (Mar. 15, 1930), p. 33. 

234 HATSCHEK, P.: Kinotechnik, 11 (Sept. 20, 1929), p. 489. 
SS6 ScHiFFE, R.: Kinemat. Weekly, 153 (Nov. 14, 1929), p. 41. 

236 CARTER, W. L.: Kinemat. Weekly, 152 (Oct. 31, 1929), p. 58. 

237 COOKE, H. L.: /. Franklin Inst., 208 (Sept., 1929), p. 319. 

238 Mot. Pict. Projectionist. 3 (Nov., 1929), p. 43. 
289 Mot. Pict. News, 39 (June 1, 1929), p. 1838. 

240 ADAM, M.: Filmtechnik, 5 (Jan. 5, 20, 1929), pp. 13 and 31. 
241 LEwiN, W.: Ed. Screen, 9 (Feb., 1930), p. 41. 

242 Ed. Screen, 8 (Dec., 1929), p. 295. 

243 Ed. Screen, 8 (June, 1929), p. 188. 

844 Ex. Herald-World, 40 (Dec. 7, 1929), p. 14. 

245 Ann. Report. Acad. Mot. Pict. Arts and Sciences, Hollywood, Cat. (1929), 
p. 9. 

246 Ex. Daily Review and Motion Pict. Today, 27 (Jan. 25, 1930), p. 4. 

247 Ex. Daily Review and Mot. Pict. Today, 27 (Jan. 11, 18, 1930), pp. 14 and 
12. 

248 Mot. Pict., 5 (Dec. 1, 1929), p. 2. 

249 Ex. Herald-World, 97 (Dec. 7, 1929), p. 32; also Ed. Screen, 8 (Dec., 1929), 
p. 298. 

250 Reports Mot. Pict. Div. U. S. Dept. Commerce (Mar. 12, 1930). 
*" Bull. Acad. Mot. Pict. Arts and Sci., No. 29 (Feb. 27, 1930). 
252 GuNTHER, W.: Filmtechnik, 5 (June 8, 1929), p. 240. 
^'SANTINI, G.: Internal. Rev. Ed. Cinemat., 1 (July, 1929), p. 26. 

254 McCLUSKY, F. D.: Ed. Screen, 8 (Nov.-Dec., 1929), pp. 260 and 297. 

255 WALTERS, O.: J. Chem. Ed., 6 (Oct., 1929), p. 1736. 
266 Ed. Screen, 8 (Nov., 1929), p. 265. 

257 Mot. Pict. 5 (Nov., 1929), p. 1. 

258 Reports Mot. Pict. Div. U. S. Dept. Commerce (Feb. 5, 1930). 

259 Ex. Herald-World, 97, Sect. 1 (Oct., 26, 1929), p. 26. 

260 Amer. Cinemat., 10 (Dec., 1929), p. 46. 

a^SiERKS, T. H.: Amer. Cinemat., 10 (Dec., 1929), p. 13. 
262 Ed. Screen, 8 (Nov., 1929), p. 265. 
263 RooN, H.: Kinotechnik, 11 (Aug. 20, 1929), p. 430. 
264 UMBEHR, H.: Filmtechnik, 5 (June 18, 1929), p. 249. 

265 Photo-Era, 63 (Nov., 1929), p. 277. 

266 STUMPF, P.: Fortschr. a. d. Gebiete d. Roent., 40 (Nov., 1929), p. 798. 

267 ROSENBERGER, H.: Amer. Cinemat., 10 (Mar., 1930), p. 37. 

268 COISSAC, G. M.: Cineopse, 12 (Jan., 1930), p. 47. 

269 Ed. Screen, 8 (June, 1929), p. 170. 

270 Bull. soc. franc, phot., 16 (Feb., 1929), pp. 39 and 41. 



122 PROGRESS IN MOTION PICTURE INDUSTRY [J- S. M. P. B. 

271 NEBLETT, C. B.: Photo-Era, 62 (June, 1929), p. 331. 

272 Chicago Tribune (Feb. 2, 1930), p. 1. 

273 JENKINS, C. F.: /. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 344. 

274 Rochester Sunday American (Oct. 31, 1929). 

275 Ex. Daily Review and Mot. Pict. Today, 27 (Jan. 18, 1930), p. 1. 

276 Ex. Herald-World, 98 (Mar. 1, 1930), p. 47. 

277 ZWORYKIN, V.: Project. Eng., 1 (Dec., 1929), p. 18. 

278 Proc. Inst. Rad. Eng., 17 (Sept., 1929), p. 1584. 

279 Filmtechnik, 5 (June 22, 1929), p. 274; Fr. Pat. 654,018. 

280 Sd. ind. phot., 2nd Series, 1 (Apr., 1930), p. 160. 

281 CRANZ, C., AND SCHARDIN, H.: Z. Physik, 56 (July, 1929), p. 147. 

282 Nature, 124 (Aug. 31, 1929), p. 338. 

283 McKAY, H. C.: Photo-Era, 63 (July, 1929), p. 58. 

284 CLERC, L. P.: Brit. J. Phot., 76 (Nov. 15, 1929), p. 681; Brit. Pat. 316,668. 

285 Camera, Philadelphia, 39 (Oct., 1929), p. 227. 

286 Ger. Pat. 472,028. 

287 Ex. Herald-World, 97 (Dec. 21, 1929), p. 40; also Film Daily, 51 (Jan. 8, 
1930), p. 1; and Mot. Pict. News, 41 (Feb. 8, 1930), p. 69. 

288 Mot. Pict. News, 41 (Apr. 19, 1929), p. 39. 

289 Reports Mot. Pict. Div. U. S. Dept. Comm. (Feb. 18, 1930). 

290 Film Daily, 51 (Mar. 31, 1930), p. 1. 

291 PECK, W. H.: Film Daily, 52 (Mar. 6, 1930), p. 19. 

292 MATTHEWS, G. E.: Amer. Cinemat., 10 (Jan., Feb., 1930), pp. 3 and 12. 
293 RODDE, M.: Bull. soc. franc, phot., 15 (Mar., 1928), p. 80. 

294 Photo-Era, 63 (Aug., Sept., 1929), pp. 103 and 162. 

295 U. S. Pats. 1,717,404; 1,717,405; 1,730,712; 1,732,432; 1,735,108; Brit. 
Pats. 310,533; 314,546; 316,236; Fr. Pats. 33,167 (add. 619,904); 651,196; 
651,355. 

296 U. S. Pats. 1,721,244; 1,729,922; 1,730,942; Canad. Pat. 293,857; Brit. 
Pats. 310,320; 314,995; 317,051; 317,060; Fr. Pats. 641,870; 650,093; 
654,243; 667,332. 

297 NAUMANN, H.: Phot. Korr., 65 (Apr., 1929), p. 177; also EGROT, L. G.: 
Kinemat. Weekly, 152 (Nov. 7, 1929), p. 52. 

298 EGROT, L. G.: Kinemat. Weekly, 152 (Oct. 10, 1929), p. 63. 

299 U. S. Pat. 1,728,426; Brit. Pats. 312,248; 316,141; 319,194; 319,195; 
Fr. Pat. 658,984; Ger. Pats. 466,302; 471,508; 475,982; 479,755; 481,301; 
484,900. 

300 Ex. Herald-World, 97 (Nov. 6, 1929), p. 36; also Mot. Pict. News, 40 (Oct. 
5, 1929), p. 1196; Film Daily, 52 (Apr. 22, 1930), p. 1. 

301 Amer. Cinemat., 10 (Dec., 1929), p. 9. 

302 Ex. Herald-World, 96 (Aug. 3, 1929), p. 48. 

303 Ex. Herald-World, 98 (Feb. 1, 1930), p. 21. 

304 Licht Bild Bilhne, 22 (Aug. 17, 1929), p. 14. 

305 U. S. Pats. 1,734,476; 1,735,142; 1,735,810; 1,735,811; 1,735,812; 1,735,- 
813; 1,736,554; 1,736,555; 1,736,557; 1,736,826; Canad. Pat. 291,636; Brit. Pats. 
316,338; 316,339; 316,367; 316,388; 317,909; 319,779; 319,924; Ger. Pats. 472,502; 
473,623; 477,878; 482,166; 483,674; 484,009; 484,306. 

306 COMSTOCK, K. M.: Movie Makers, 4 (Dec., 1929), p. 785. 



July, 1930] PROGRESS IN MOTION PICTURE INDUSTRY 123 

307 Amat. Films, 11 (Oct., 1929), p. 39. 

308 BRISTOL, W. H.: J. Soc. Mot. Pict. Eng., 14 (Mar., 1930), p. 361. 

309 Movie Makers, 4 (July, 1929), p. 480. 
Photo-Era, 63 (Nov., 1929), p. 284. 

311 Phot. Dealer, 44 (Mar., 1930), p. 132. 

312 PAUDER, H.: Film fur Alle, 3 (Oct., 1929), p. 290. 

313 Movie Dealer, 2 (Oct., 1929), p. 19. 

814 McKAY, H. C.: Photo-Era, 63 (July, 1929), p. 56. 

315 U. S. Pats. 1,727,356; 1,727,891; 1,735,155; 1,739,113; Brit. Pat. 311,230; 
Fr. Pats. 596,907; 33,302 (add. 618,721); 651,788; 653,115; 656,207; Ger. Pats. 
461,211; 461,673; 483,737. 

316 Movie Makers, 4 (July, 1929), p. 481. 

317 Movie Makers, 4 (Apr., 1929), p. 257. 

318 Licht Bild Buhne, 22 (Oct. 5, 1929), p. 238. 

319 Amer. Cinemat., 10 (Nov., 1929), p. 20. 
320 RiCHMAN, A.: Movie Makers, 4 (Sept., 1929), p. 567. 

321 Movie Dealer, 2 (Oct., 1929), p. 18. 

322 Amer. Cinemat., 10 (Mar., 1930), p. 31. 

323 U. S. Pat. 1,735,468; Brit. Pats. 316,135; 316,257; 316,258; 319,644; 
Fr. Pats. 644,324; 649,914; 651,851; 658,121; 658,122; 658,123; 658,890. 

324 Amat. Phot., 68 (July 10, 1929), p. 40. 

325 Amat. Films, 2 (Dec., 1929), p. 89. 

326 Amat. Films, 2 (Nov., 1929), p. 73. 

327 Amer. Cinemat., 10 (July, 1929), p. 33. 

328 Photo-Era, 63 (July, 1929), p. 58. 

329 U. S. Pats. 1,728,244; 1,735,162; Fr. Pat. 640,485. 

330 HUGON, P. D.: Movie Makers, 4 (July, 1929), p. 452. 

331 WALLER, F.: Movie Makers, 4 (July, 1929), p. 441. 

332 Sci. Amer., 142 (Apr., 1930), p. 299. 

333 Photo Revue, 41 (Feb. 1, 1929), p. 33; ibid., 41 (Apr. 15, 1929), p. 113; 
Photographe, 16 (Oct., 1929), p. 453; Brit. J. Phot., 76 (Nov. 22, 1929), p. 693; 
Amat. Films, 2 (Dec., 1929), p. 104. 

334 U. S. Pat. 1,723,701; Brit. Pat. 318,040. 

335 Ex. Herald-World, 98 (Mar. 8, 1930), p. 25. 

336 Film Daily, 51 (Jan. 27, 1930), p. 1. 

337 Ex. Herald-World, 98 (Feb. 8, 1930), p. 30. 

338 Ex. Herald-World, 98 (Feb. 1, 1930), p. 29; also Mot. Pict. Projectionist, 
3 (Nov., 1929), p. 47. 

339 Reports Mot. Pict. Div. U. S. Dept. Commerce (Apr. 16, 1930). 

340 Mot. Pict., 5 (Dec., 1929), p. 4. 

341 GOLDEN, N. D.: Report U. S. Dept. Commerce (Feb. 5, 1930). 

342 Film Daily, 51 (Jan. 21, 1930), p. 1. 

343 Film Daily, 50 (Oct. 27, 1929), p. 7. 

344 Film Daily, 50 (Oct. 17, 1929), p. 10. 

345 Motion Pictures Abroad, Reports Mot. Pict. Div. U. S. Dept. Commerce 
(Jan. 29, Feb. 1, Feb. 14, Feb. 24, Mar. 6, Mar. 27, 1930). 

346 NORTH, C. J.: Reports Mot. Pict. Div. U. S. Dept. Commerce (Mar. 24, 1930). 
847 Year Book of Motion Pictures, Film Daily, N. Y. (1930), p. 706. 



ABSTRACTS 



The Editorial Office will welcome contributions of abstracts and book reviews 
from members and subscribers. Contributors to this section are urged to give 
correct and complete details regarding the reference. Items which should be 
included in abstracts are: 

Title of article 

Name of author as it appears on the article 

Name of periodical and volume number 

Date and number of issue 

Page on which the reference is to be found 
In book reviews, the following data should be given : 

Title of book 

Name of author as it appears on the title page 

Name of publishing company 

Date of publication 

Edition 

Number of pages and number of illustrations 

The customary practice of initialing abstracts and reviews will be followed. 
Contributors to this issue are as follows: G. L. Chanier, E. E. Richardson, 
Clifton Tuttle, and the Monthly Abstract Bulletin of the Kodak Research Labora- 
tories. 

Camera Battery. K. STRUSS. Intern. Phot., 1, July, 1929, p. 17. This de- 
scribes a method of arranging a battery of cameras for simultaneous photography 
of action in dialog pictures. Six cameras were used in one scene and the total time 
required for completing the photography was reduced considerably. Kodak Abstr. 
Bull. 

Mitchell Camera Adapted to Multicolor. Intern. Phot., 1, January, 1930, 
p. 15. The Mitchell camera has been adapted to multicolor photography. In 
three months of development, the principal difficulty overcome was caused by the 
back coating picking up on the aperture and pressure plates when the two nega- 
tive films used in the process were put under pressure. C. M. T. 

Optical Systems for Two-Colour Cinematography. Brit. J. Phot., Colour 
Supp., 77, Jan. 3, 1930, p. 2. Two recently accepted patent specifications 
(see Br. Pat. 319,194) describe optical systems for the production and projection 
of two-color motion picture films. A prism light dividing system is designed to 
produce two-color component images, which lie corner to corner across the 
diagonal of the standard area. The twin lens system is intended for use inter- 
changeably with the ordinary lens on a projector. C. M. T. 

New Super Simplex Projector. Bioscope (Mot. Cinema Technique}, 82, 
Jan. 8, 1920, p. vii; Projection Eng., 2, February, 1930, p. 29. An illustrated 
description of the Super Simplex 25 mm. projector. In this device the shutter, 
which is supplied with tilted blades, is mounted between the condenser and the 
aperture in such a manner as to direct a current of air on the film and surrounding 
124 



ABSTRACTS 125 

mechanism. Other features provide for automatic centering in changing over 
from silent film to sound-on-film and for the attachment of the magnascope lens. 

C. M. T. 

Photographic Aspects of Sound. A. PBRBIRA. Cinema, 33, Dec. 4, 1929, p. 
xvi. Among causes of lack of quality of sound films are the following: imperfect 
contact between negative and positive in the printer; slipping between negative 
and positive ; scattering of light in the film ; irregular motion of the film in camera 
or printer caused by sprocket teeth errors; sharp focus of the "sound beam" 
in recording. Unwanted sounds are caused by splices, reflections from edges of 
printer gates, hair-like spaces between sound and picture caused by a convex- 
sided camera mask, and fine serration of the black line between sound and pic- 
ture. Kodak Abstr. Butt. 

Photographing Sound. Photo-Era, 64, March, 1930, p. 160. Various methods 
of analyzing and photographing sound are discussed. Those considered are: 
Foley and Souder's method utilizing two spark gaps in which one produces the 
sound and the other furnishes the light (a record of the shadow of the wave being 
obtained); the method used by Koenig, Nichols, and Merrit, in which photo- 
graphs are made of a gas flame, which vibrate in response to the sound waves ; 
the phonodeik of D. C. Miller, which uses a vibrating mirror mounted on a tiny 
spindle; a similar system used by A. E. Bawtree; the sonometer of A. Hilger 
makes use of a platinized diaphragm as the refracting medium, and the system 
whereby the sound waves are converted into electromagnetic waves which in 
turn operate an oscillograph of the Blondel type. Kodak Abstr. Bull. 

Technical Problems of Talking Films. K. SCHINZEL. Kinotechnik, 11, 
July 5, 1929, p. 346. The first of this series of articles deals with the general 
methods used for production of sound films and considers in a general way the 
requirements as to frequency range, width of sound track available, and similar 
factors. He considers the use of paper film both for photographic and magnetic 
records. Kodak Abstr. Bull. 

Technical Problems of Sound Film. II. K. SCHINZEL. Kinotechnik, 11, 
Sept. 5, 1929, p. 464. This instalment is a discussion of photo-chemical problems. 

C. M. T. 

Making Sound Films. II. The Photographic Stock Factor. T. T. BAKER. 
Kinemat. Weekly, 155, Jan. 2, 1930, p. 125. For variable width sound recording, 
the necessary characteristics of the emulsion are freedom from fog and from 
graininess, while for variable density sound recording a straight line form of the 
characteristic curve is the ideal. Methods of examination of the characteristics 
of negative or positive stock are simply explained. Kodak Abstr. Bull. 

New Sound Picture Laboratory. H. A. PRICE. Bell. Lab. Record, 8, February, 
1930, p. 257. This description of the new sound picture addition to the Bell 
Laboratories includes photographs and diagrams of the layout. Both film and 
disk recording and reproducing are planned, and a complete film finishing de- 
partment has been installed in this model laboratory. C. M. T. 

The Decibel. JOHN DUNSHEALTH. Projection Eng., 2, May, 1930, p. 15. 
The origin of the word Decibel. E. E. R. 

Architectural Acoustics. P. R. HEYL. Projection Eng., 2, May, 1930, p. 15. 
A discussion in which the fundamental principles governing the construction 
of an acoustically successful auditorium are stated. An example is given which 



126 ABSTRACTS [J. S. M. P. E. 

illustrates the application of these principles in the planning of a new auditorium. 

E. E. R. 

Monitor and Recording Room. Cinema, 33, Dec. 4, 1929, pp. xv and xvi. 
At the Wembley studios, a mobile monitoring box containing the amplifiers is 
used. Klangfilm recording apparatus will be used. British Talking Pictures 
recording system, using the "photeon" lamp is at present employed. The sound 
record is identified by photographing on the film at intervals of an inch or two 
a lantern slide carrying the scene and shot numbers. Each half minute, figures 
up to ten in Morse code are printed on the side of the film opposite the sound track. 
Corresponding figures are recorded on the picture negative in the space to be 
occupied by the sound track. Between shots, a punch hole is made on the edge 
of the film, indicating where cuts can be made in processing. The "photeon" 
lamp is in the anode circuit of a single L. S. 5 valve, having 900 volts anode poten- 
tial, and an output of 15 milliamperes. The lamp resembles a minute arc lamp, 
with a fine iron cathode and tungsten anode. Kodak Abstr. Bull. 

Britain's Latest Sound Studio. Cinema, 33, Dec. 4, 1929, p. xii. The article 
presents a description of the new sound studio of British Talking Pictures, Ltd., at 
Wembley. All lighting is controlled from overhead, and there are no cables on 
the floor. An outstanding feature is the use of intercommunicating telephones. 
The Plenum ventilation system is used. For sound insulation, the walls consist 
of one main shell of brick. The structure is of concrete blocks with triangular 
breeze blocks inside. Eight inches away from this is a lining of insulite, supported 
on a light wooden frame, and having no mechanical connection with the main 
structure. The wood floor rests on a three-inch layer of a kind of tarmac. The 
studio is 120 by 90 by 30 feet, to the top gallery, and about 20 feet to a second 
gallery running round the wall. A tank 33 feet square by 9 feet deep is pro- 
vided. Kodak Abstr. Bull. 

Lighting a Modern Studio. Cinema, 33, Dec. 4, 1929, p. xii. At the Wembley 
studios of British Talking Pictures, Ltd., incandescent lighting is used throughout. 
Lamps are massed in banks hung on cables which travel on overhead rails. The 
banks can be tilted to any desired angle. In the galleries, twelve switchboards 
feed eight mobile trucks each capable of handling 3000 amperes. The lamps are 
500 watt, arranged in banks, and each lamp is provided with a reflector following 
the shape of the bulb. Lamps consuming several kilowatts are also available. 
Ventilation is so efficient that the heating is not noticeable on the floor. Kodak 
Abstr. Bull. 

New Fearless Silent Camera. A. REEVES. Intern. Phot., 1, January, 1930, 
p. 34. It is claimed that this sound and picture camera can be used at a distance 
of ten feet from the microphone. It is equipped with a high pressure oiling sys- 
tem, a unique focussing arrangement, and an automatic film tension control. 
Accessories are furnished which can be used for wide pictures and for Multicolor. 

C. M. T. 

Continuous Projectors and Colour. Cinema, 33, Dec. 4, 1929, p. vii. The 
Photo- Vision continuous projector, invented by W. E. John, was demonstrated in 
London on Nov. 7, 1929. It uses a series of lenses, each independently mounted, 
moving in a D -shaped slot. The frames are centered to the lenses by lengthening 
or shortening the path of travel of the film from one reel to the other. A special 
mirror gives an elongated image of the arc, and the carbons are arranged so as to 



July, 1930] ABSTRACTS 127 

cast no shadow on the mirror. For wide film, it is proposed to use standard stock 
run through the projector sideways. The advantages of the continuous pro- 
jector for additive color cinematograph projection are indicated. Kodak Abstr. 
Bull. 

Excellence in Auditoriums. W. A. MACNAIR. Bell Lab. Record, 8, March, 
1930, p. 325. MacNair gives a review of work done to decide on a criterion for 
good quality of reproduction of music and speech. It has been found that the 
product of the reverberation time and the loudness sensation produced by a stand- 
ard source is constant for all good auditoriums. The absorption characteristics 
for each frequency can be deduced from known data and the results check the 
known fact that an extremely reverberant room is usually acoustically good with 
a large audience present. Kodak Abstr. Bull. 

A Year of Talkies. Survey of New Systems and Working Conditions. R. H. 
CRICKS. Kinemat. Weekly, 155, Jan. 2, 1930, p. 133. Eighteen sound repro- 
duction sets are available to the British exhibitor, of which eleven are British 
products, six American, and one German. The use of selenium cells instead of 
photo-electric cells is being developed. C. M. T. 

Moving Picture Industry Has Four Billion Capital. Projection Eng., March, 
1930, p. 32. A summary of the report of the International Labor Bureau on 
classified statistics regarding the motion picture industry. G. L. C. 

Birth of the Cinema. W. DAY. Intern. Phot., 1, July, 1929, p. 3. Neglecting 
certain primitive steps we can view the invention of the camera obscura about 
1437 as the first step in the development of modern moving pictures. Early in 
the seventeenth century Athanasius Kircher described a primitive magic lantern. 
To Wedgewood, Niepce, Daguerre, and Fox-Talbot we are indebted for the 
beginnings of modern photographic processes. To bring about the invention of 
motion pictures, knowledge of persistence of vision was necessary. Roget ap- 
parently first recorded observations on this subject in a paper read before the 
Royal Society. The Thaumatrope, Phenakistoscope, Stroboscope, Daedaleum, 
and Zoetrope were early instruments using this effect to give the appearance of 
movement. John Rudge first portrayed movement using successive lantern 
slides, but his successors, Friese-Greene, Beale, Linnet, Ross, and Edison, made 
improvements which culminated in Marey's Stereo-Zoetrope. Muybridge first 
used pictures taken in rapid succession with a number of cameras whose shutters 
were electrically controlled. C. M. T. 

Simulating Sunlight. M. LUCKIESH. Gen. Elec. Rev., 33, February, 1930, 
p. 89. The new General Electric "Sunlamp" is described. Kodak Abtr. Bull. 

Glossary of Cinematic Terms. II. Amat. Films, 2, January, 1930, p. 110. 
This is the second installment of a series of technical and general phrases used in 
cinematography. C. M. T. 



BOOK REVIEWS 

Technical Digest Fundamentals of Sound Recording and Reproduction for 
Motion Pictures. Academy of Motion Picture Arts and Sciences, Hollywood, 
Calif., loose leaf, 1930, 216 pp. Authoritative articles on sound motion pictures 
will be issued from time to time in the form of loose leaf additions to the Technical 
Digest. Most of the material thus far included is based upon lecture-demonstra- 
tions given before the School in Fundamentals of Sound Recording and Re- 
production conducted by the Academy in 1929. It is obviously impossible to 
present a comprehensive review of a series of papers covering so many phases of 
sound motion picture theory and technic. Some of the foremost authorities in 
the field have contributed well illustrated articles on the history of sound record- 
ing, physical and physiological aspects of sound, acoustics, psychological factors 
affecting the illusion of sound pictures, photographic theory, and the optical tech- 
nic peculiar to the various recording processes. C. M. T. 

Scenario Writing. MARION NORRIS GLEASON. Amer. Photographic Pub. Co., 
Boston, 1929, $3.50, 308 pp. The purpose of this book is to show simply and 
clearly to the amateur cinematographer the construction of motion pictures con- 
sidered as drama. In working up a finished production the scenario's importance 
is very greatly stressed, and various hints are given on choosing its plot. The 
entire field of childhood stories can be drawn from if children are to be the au- 
dience. If an organized group is producing the picture, they may often have 
country clubs, private yachts, fire departments, and universities at their command 
and hence an elaborate plot may be developed. All have at their disposal an 
unlimited amount of written story material of the world fiction, history, and 
classics. Since the experimental field has only been touched much can now be 
done with color and sound. The amateur enthusiast can learn a great deal from 
this interesting book. It will be of great value to the club planning its first pro- 
duction since it shows the background behind the successfully made professional 
pictures. Twenty scenarios are given to be used as models and there are also 
sixteen illustrations from some amateur productions. Kodak Abstr. Bull. 



128 



SOCIETY OF MOTION PICTURE 
ENGINEERS 

OFFICERS 

President 
J. I. CRABTREE, Eastman Kodak Co., Rochester, New York 

Past President 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

Vice-Presidents 

H. P. GAGE, Corning Glass Works, Corning, N. Y. 
K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 

Secretary 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

Treasurer 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

Board of Governors 

H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Roches- 
ter, N. Y. 

J. I. CRABTREE, Research Laboratory, Eastman Kodak Co., Roches- 
ter, N. Y. 

J. A. DUBRAY, Bell & Howell Co., 1801-1815 Larchmont Ave., Chi- 
cago, 111. 

H. P. GAGE, Corning Glass Works, Corning, N. Y. 

K. C. D. HICKMAN, Research Laboratory, Eastman Kodak Co., 
Rochester, N. Y. 

W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood 
Blvd., Los Angeles, Calif. 

P. MOLE, Mole-Richardson, Inc., 941 N. Sycamore Ave., Holly- 
wood, Calif. 

M. W. PALMER, Paramount-Famous-Lasky, Inc., 6th & Pierce Aves., 
Long Island City, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

S. ROWSON, Ideal Films, Ltd., 76 Wardour St., London, W. 1, England 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 

129 



130 



[J. S. M. P. E. 



J. G. CAPSTAFF 



J. W. COFFMAN 



E. ADAMS 

C. L. GREGORY 



COMMITTEES 
1929-1930 

Color 

W. V. D. KELLEY, Chairman 

W. T. CRESPINEL F. E. IvES 

Convention 

W. C. KUNZMANN, Chairman 

W. C. HUBBARD M. W. PALMER 

Historical Committee 

F. J. WILSTACH Chairman 

C. F. JENKINS A. S. NEWMAN 

O. NELSON T. RAMS A YE 



Journal 

L. A. JONES, Chairman 

J. W. COFFMAN H. T. COWLING W. C. HUBBARD 

J. H. KURLANDER 

Membership and Subscription 

H. T. COWLING, Chairman 

C. BARRELL J. DEFRENES B. E- NORRISH 

J. W. BOYLE E. R. GEIB I. ROSEMAN 

W. H. CARSON D. E. HYNDMAN E. C. SCHMITZ 

W. CLARK J. KLENKE J. L. SPENCE 

L. W. DAVEE M. L. MISTRY F. ZUCKER 

Papers 

J. W. COFFMAN, Chairman 

M. C. BATSEL C. R. HANNA G. E. MATHER 

F. J. CADENAS K. C. D. HICKMAN R. F. NICHOLSON 

J. A. DUB RAY E. HUSE J. B. TAYLOR 

O. M. GLUNT D. E. HYNDMAN 



Progress 

G. E. MATTHEWS, Chairman 
M. ABRIBAT J. B. ENGL 

J. A. BALL R. E. FARNHAM 

J. BOOLSKY H. B. FRANKLIN 

W. CLARK E. R. GEIB 

K. GEYER 



A. C. HARDY 
R. C. HUBBARD 
G. F. RACKETT 
S. K. WOLF 



July, 1930] 



H. W. DREYER 
G. C. EDWARDS 
P. H. EVANS 
T. FAULKNER 
J. H. GOLDBERG 



COMMITTEES 

Projection 

L. M. TOWNSEND, Chairman 

C. GREENE R. MIEHLINO 

H. GRIFFIN W. B. RAYTON 

N. M. LAPORTE F. H. RICHARDS 

R. H. McCuLLOUGH H. B. SANTEE 

W. A. MCNAIR D. F. WHITING 



131 



F. C. BADGLEY 



Publicity 

W. WHITMORE, Chairman 
B. W. DEPUE 
G. E. MATTHEWS 
G. F. RACKETT 



O. A. Ross 



J. W. COFFMAN 



Solicitation 
E. P. CURTIS, Chairman 



E. A. WILLIFORD 



Standards and Nomenclature 



M. C. BATSEL 
W. H. CARSON 
L. W. DAVEE 
A. DEBRIE 
L. DEFOREST 
J. A. DUBRAY 
E. W. ENGSTROM 



A. C. HARDY, Chairman 

P. H. EVANS G. F. RACKETT 

R. E. FARNHAM W. B. RAYTON 

H. GRIFFIN V. B. SBASE 

R. C. HUBBARD T. E. SHEA 

L. A. JONES J. P. SPENCE 

N. M. LAPORTE E. I. SPONABLE 

G. MITCHELL L. T. TROLAND 
W. P. POWERS 



L. J. BUTTOLPH 



Studio Lighting 

A. C. DOWNES, Chairman 
R. E. FARNHAM 
K. C. D. HICKMAN 



M. W. PALMER 



J. C. AALBERG 
F. A. BENFORD 
A. C. DOWNES 



Theater Lighting 

C. E. EGELER, Chairman 
F. FALGE 
R. E. FARNHAM 



C. GREENE 
E. HUSE 
L. A. JONES 



132 COMMITTEES [j. s. M. P. E. 

CHICAGO SECTION 

J. A. DUBRAY, Chairman O. F. SPAHR, Manager 

J. B. JENKINS, Secy.-Treas. O. B. DEPuE, Manager 



LONDON SECTION 

SIMON ROWSON, Chairman 

A. NEWMAN, Vice-Chairman PAUL KIMBERLEY, Manager 
L. BVELEIGH, Secretary ALAN WILLIAMSON, Manager 

H. WOOD, Treasurer WILLIAM VINTEN, Manager 

NEW YORK SECTION 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. K. HYNDMAN, Sec.-Treas. T. B. SHEA, Manager 



PACIFIC COAST SECTION 

P. MOLE, Chairman C. DUNNING, Manager 

G. F. RACKETT, Sec.-Treas. B. HUSE, Manager 

Membership Committee 

J. COURCIER, Chairman 
B. JEWELL 

' Papers and Programs 

B. HUSE, Chairman 



July, 1930] MINUTES OF SECTIONS 133 

CHICAGO SECTION 

The organization meeting of the Chicago Section of the Society 
was held May 31, 1930, at the City Club. Mr. O. B. DePue and Mr. 
O. F. Spahr were elected governors. Mr. J. A. Dubary, Mr. Fred 
Kranz, and Mr. E. S. Pearsall, Jr., were elected to serve on the Papers 
and Program Committee. Mr. B. W. Depue was appointed as a 
Publicity Committee of one. 

Boundaries of the Section were proposed as follows: The eastern 
boundary shall be a north and south line through a point 50 miles west 
of Cleveland; the western boundary shall be a north and south line 
running through a point 50 miles west of Denver ; the north and south 
boundaries shall be those of the United States. 

A motion was passed that a dinner meeting be held once a month 
in a place to be selected by the governors, and that the meeting of 
any month might be cancelled by the governors at their discretion. 

LONDON SECTION 
April, 1930 

Sir Oliver I v odge, making his first appearance at a cinematograph 
trade function, was guest of honor at the first annual dinner of the 
London Section. A program of films, starting with the first Lumiere 
film shown upon its original instrument by Matt Raymond, its origi- 
nal projectionist, and ending with a showing of present day talkies 
with equipment installed by Western Electric, followed the dinner. 

The last general members' meeting of the session was held at the 
headquarters of the Royal Photographic Society on April 14th, when 
Mr. N. Fleming of the National Physical Laboratory read a paper 
on the "Acoustics of Buildings." 

NEW YORK SECTION 

A meeting of the section was held in the Engineering Societies 
Building, April 16, 1930. 

Papers were presented by Mr. Hall of the New York Times on 
"The Critic's Viewpoint on Talking Pictures," by Mr. Mendoza on 
his experiences in orchestra direction before the microphone, and by 
Mr. Cook on "The Aperture Effect." A schedule of eight meetings 
per year has been adopted by the section. 



134 SOCIETY NOTES [j. S. M. p. E. 

A meeting is scheduled for June 12, 1930, at the Engineering So- 
cieties Building. At this meeting Mr. Townsend will present the re- 
port of the Projection Committee and Messrs. Lette and Wolf will 
present a paper on "Factors Governing Size of Sound Reproducing 
Equipment in Theaters." 

PACIFIC COAST SECTION 

The third meeting of the season was held on one of the sound 
stages of the Metropolitan Sound Studios, Inc. An open discussion of 
the type of programs desired by the Section and of regular vs. ir- 
regular meeting times was held. It was decided to continue the pres- 
ent policy of flexible meeting dates. 

Mr. Richardson was elected as delegate to the spring convention 
in Washington. Mr. George Mitchell was selected to represent the 
Section in discussions of wide film problems at the convention. 

Results obtained with the Douglass wide film panorama lens were 
demonstrated by projecting pictures from standard 35 mm. film. 

Recent Multicolor films were shown by Mr. Harry Fisher. 

SOCIETY NOTES 

At the meeting of the Board of Governors held at the Engineering 
Societies Building, New York, N. Y., Tuesday, June 3rd, a large num- 
ber of business matters were transacted including the following: 

1. A committee was appointed to draw up a report for circulation 
to the sections of the Society, explaining in detail what expenditures 
are justifiable, and also to consider the desirable geographical bound- 
aries of the various sections in the United States. The Board was in 
doubt as to whether the boundaries of the various sections should be 
limited to an area within a definite radius from the section's head- 
quarters or whether the three sections, namely, New York, Chicago, 
and the Pacific Coast should include the entire United States. 

2. The Board having satisfied itself that the financial situation of 
the Society justifies the appointment of an editor-manager, a motion 
was made and passed as follows: "A person of high caliber shall be 
secured to edit and publish the JOURNAL from a central office and also 
to transact the routine business of the Society, this individual to be 
supplied with qualified editorial and clerical assistants." 



July, 1930] SOCIETY NOTES 135 

3. A motion was made and passed: That applications for mem- 
bership originating in the territory of any section of the Society are 
to be first submitted for comment to the local section's Board of 
Managers. 

4. A committee was appointed consisting of J. H. Kurlander and 
W. M. Palmer to recommend suitable headquarters for the Society 
in New York City. The Board recommended that the location should 
be within a reasonable distance of the Grand Central Terminal. 

5. As a result of a proposal that all discussions of papers presented 
at meetings be eliminated from the JOURNAL, the Board recommended 
that the editor should continue to edit and publish discussions of 
papers in accordance with past practice. 

6. The Board approved a recommendation of the Publicity Com- 
mittee to permit trade papers to abstract the text of papers presented 
at conventions to an extent not exceeding 20 per cent of the text of any 
paper. 

7. A revised application blank submitted by the Secretary was 
approved. The new blank provides for a more complete description 
of an applicant's qualifications. 

8. The Treasurer reported on the Washington convention re- 
ceipts and expenses as follows: 

Gross Expenses $2460. 18 

Gross Receipts 2305 . 50 



Deficit $ 154.68 

9. A motion was made and passed that the President appoint a 
committee to consider the establishment of a post graduate course in 
motion picture engineering in a number of selected universities. 



WANTED AN EDITOR-MANAGER 

In accordance with a resolution of the Board of Governors applica- 
tions are hereby invited for a combined business manager of the 
Society and editor of the JOURNAL who will be located at the head- 
quarters of the Society in New York City. The manager-editor will 
be supplied with capable editorial and clerical assistants and his 
duties will be (a) to edit the JOURNAL under the jurisdiction of the 



136 CONSTITUTION AND BY-LAWS [J. S. M. P. E. 

Board of Editors, (b) to transact the routine business of the Sec- 
retary and Treasurer and the various committee chairmen, and (c) 
to assist the President in coordinating the various activities of the 
Society. 

Desirable qualifications of the applicant include a pleasing person- 
ality, managerial and technical editorial ability, and a broad knowl- 
edge of the motion picture industry. The salary will be not less 
than $6000 per year. 

Applications should be forwarded to Mr. J. H. Kurlander, Secre- 
tary, 2 Clearfield Avenue, Eloomfield, N. J., not later than July 15th. 



CONSTITUTION AND BY-LAWS AS AMENDED OCTOBER, 1929 AND 

MAY, 1930 

Article 1. Name. 

The name of this association shall be Society of Motion Picture Engineers. 
Article 2. Objects. 

Its objects shall be: Advancement in the theory and practice of motion picture 
engineering and the allied arts and sciences, the standardization of the mechanisms 
and practices employed therein, the maintenance of a high professional standing 
among its members, and the dissemination of scientific knowledge by publication. 
Article 3. Eligibility. 

Any person of good character may be a member in any class for which he is 
eligible. 
Article 4. Officers. 

The officers of the Society shall be a President, the Past- President, a Senior Vice- 
President, a Junior Vice- President, a Secretary, a Treasurer, and a Board of Gov- 
ernors. 

All officers shall hold office for one year, or until their successors are chosen, 
except the Board of Governors, as hereinafter provided, and the Vice-Presidents, 
one of which latter shall be elected each year to serve for two years. 
Article 5. Board of Governors. 

The Board of Governors shall consist of the President, the Past- President, the 
Senior Vice-President, the Junior Vice- President, the Secretary, the Treasurer, 
the Section Chairmen, and four other Active Members, two of which last named 
shall be elected each year to serve for two year terms. 
Article 6. Meetings. 

There shall be an annual meeting, and such other meetings as stated in the By- 
Laws. 
Article 7. Amendments. 

This Constitution may be amended as follows : Amendments shall be approved 
by the Board of Governors and shall be submitted for discussion at any regular 
members' meeting. The proposed amendment and complete discussion then 
shall be submitted by publication to the entire Active membership together with 
letter ballot as soon as possible after the meeting. Two-thirds of the vote cast 
within sixty days after mailing shall be required to carry amendment. 



July, 1930] CONSTITUTION AND BY-LAWS 137 

BY-LAWS: 
BY-LAW I 

MEMBERSHIP 

SECTION 1 . The membership of the Society shall consist of Honorary Members, 
Active Members, Associate Members, and Sustaining Members. 

An Honorary Member is one who has gained high distinction in the science of 
motion picture engineering or the allied arts of sciences. 

Honorary membership may be granted upon recommendation of the Board 
of Governors when confirmed by a four-fifths majority vote of the Active 
Members present at any regular meeting of the Society. An Honorary Member 
shall be exempt from all dues. 

An Active Member is one who shall be not less than 25 years of age, and shall be: 

(a) A motion picture engineer by profession. He shall have been in the prac- 
tice of his profession for a period of at least three years and shall have taken 
responsibility for the design, installation, or operation of systems or apparatus 
pertaining to the motion picture industry. 

(b) A person regularly employed in motion picture or closely allied work, who 
by his inventions or proficiency in motion picture science or as an executive of a 
motion picture enterprise of large scope, has attained a recognized standing in the 
motion picture profession. In case of such an executive, the applicant must be 
qualified to take full charge of the broader features of motion picture engineer- 
ing involved in the work under his direction. 

An Associate Member is one who shall be not less than 21 years of age, and shall 
be a person who is interested in or connected with the study of motion picture 
technical problems or the application of them. An Associate Member is not 
privileged to vote. 

A Sustaining Member is an individual, a firm, or corporation contributing 
to the financial support of the Society. 

SECTION 2. All applications for membership or transfers shall be made on 
blank forms provided for the purpose, shall give a complete record of the ap- 
plicant's education and experience, and shall be accompanied by the required en- 
trance or transfer fee. 

SECTION 3. Applicants for Active membership shall give as references at least 
three Active members in good standing, and for Associate membership, at least 
one Active member in good standing. Applicants may be elected to membership 
by a three-fourths majority vote of the members and the Board of Governors. 

SECTION 4. Active and Associate membership becomes effective upon pay- 
ment in full of the entrance fee. 

BY-LAW II 

OFFICERS 

SECTION 1. An officer shall be an Active Member of not less than one year's 
standing. 

SECTION 2. Vacancies in the Board of Governors, except that of the Presi- 



138 CONSTITUTION AND BY-LAWS [j. s. M. p. E. 

dent, shall be filled by the Board of Governors until the Annual meeting of the 
Society. 

In case of a vacancy, the senior Vice-President shall fill the office of President, 
until the next Annual meeting. 

BY-LAW III 
BOARD OF GOVERNORS 

SECTION 1. The Board of Governors shall transact the business of the Society 
between regular members' meetings, and shall meet at the call of the President. 

BY-LAW IV 
MEETINGS 

SECTION 1. The location of each meeting of the Society shall be determined 
by the Board of Governors, after submitting not less than two places to be 
considered by the entire membership, the Board preferably selecting the place 
receiving the majority choice. 

SECTION 2. Active Members only shall be entitled to vote. 

SECTION 3. A quorum of the Society shall consist in number of one-tenth of 
the total number of Active Members as listed in the Society's records at the close 
of the last fiscal year; and of the Board, a majority. 

SECTION 4. Special meetings may be called by the President and upon the re- 
quest of any three members of the Board of Governors, not including the Presi- 
dent. 

BY-LAW V 

DUTIES OF OFFICERS 

SECTION 1. The President shall preside at all business meetings of the Society; 
he shall appoint all committees and be an ex-officio member of the same; he shall 
perform the duties pertaining to this office. 

SECTION 2. A Vice-President, in the absence of the President, shall preside at 
meetings and perform the duties of the President. 

SECTION 3. The Secretary shall keep a record of all meetings; he shall conduct 
the correspondence relating to his office, and shall have the care and custody 
of records, and the seal of the Society. 

' SECTION 4. The Treasurer shall have charge of the funds of the Society, and 
disburse the same, as and when authorized by the Board of Governors, subject 
to the approval of the President and Secretary. He shall make an annual report, 
duly audited, to the Society, and a report at such other times as may be re- 
quested. He shall be bonded in an amount to be determined by the Board of 
Governors, and his bond filed with the Secretary. 

BY-LAW VI 
ELECTIONS 

SECTION 1. All officers and four Governors shall be elected to their respective 
offices by a majority of ballots cast by the Active Members in the following man- 
ner: 



July, 1930] CONSTITUTION AND BY-LAWS 139 

Not less than three months prior to the Annual Fall Convention, the Board of 
Governors, having invited nominations from the active membership by letter form 
not less than forty days before the Board of Governors' meeting, shall nominate 
for each vacancy several suitable candidates. The Secretary shall then notify 
these candidates of their nomination in order of nomination and request their con- 
sent to run for office. From the list of acceptances, not more than two names for 
each vacancy shall be selected by the Board of Governors and placed on a letter 
ballot. A blank space shall also be provided on this letter ballot under each office 
in which space the names of any Active Members other than those suggested by 
the Board of Governors may be voted for. The balloting shall then take place. 

The ballot shall be enclosed in a blank envelope which is enclosed in an outer 
envelope bearing the Secretary's address and a space for the member's name and 
address. One of these shall be mailed to each Active Member of the Society, 
not less than forty days in advance of the Annual Fall Convention. 

The voter shall then indicate on the ballot one choice for each office, seal the 
ballot in the blank envelope, place this in the envelope addressed to the Secretary, 
sign his name and address on the latter, and mail it in accordance with the in- 
structions printed on the ballot. 

The sealed envelope shall be delivered by the Secretary to a committee of tellers 
appointed by the President at the Annual Fall Convention. This committee 
shall then examine the return envelopes, open and count the ballots, and announce 
the results of the election. 

BY-LAW VII 
DUES AND INDEBTEDNESS 

SECTION 1. The entrance fees for all applicants shall be $30.00 for admission 
to the grade of Active Member, and $20.00 for admission to the grade of Associate 
Member. 

SECTION 2. The transfer fees from Associate to Active grade shall be the dif- 
ference between the above mentioned fees, or $10.00. 

SECTION 3. The annual dues shall be $20.00 for Active Members, and $10.00 
for Associate Members, payable on or before October 1st of each year. Current 
or first year's dues for new members, dating from the notification of acceptance 
in the Society, shall be prorated on a quarterly basis, said quarters beginning 
October 1st, January 1st, April 1st, and July 1st. Ten dollars of these dues 
shall apply for annual subscription to the monthly publication. 

SECTION 4. Annual dues shall be paid in advance. All Active Members 
in good standing, who shall have paid dues for the preceding year, may vote or 
otherwise participate in the meeting. 

SECTION 5. Members shall be considered delinquent whose dues remain un- 
paid for four months. Members who are in arrears of dues for 30 days, after 
notice of such delinquency, mailed to their last address of record, shall have the 
names posted at the Society's headquarters which shall be the office of the Secre- 
tary, and notices of such action mailed them. Two months after becoming de- 
linquent, members shall be dropped from the rolls if non-payment is continued. 

SECTION 6. Any member may be suspended or expelled for cause by a majority 



140 CONSTITUTION AND BY-LAWS [J. S. M. p. E. 

vote of the entire Board of Governors; provided, he shall be given notice and a 
copy in writing of the charges preferred against him, and shall be afforded op- 
portunity to be heard ten days prior to such action. 

BY-LAW VIII 
EMBLEM 

SECTION 1. The emblem of the Society shall be a facsimile of a four-hole film- 
reel, with the letter S in the upper center opening, and the letters M, P, and B in 
the three lower openings, respectively. In the printed emblem, the four-hole 
openings shall be orange, and the letters black, the remainder of the insignia being 
black and white. The Society's emblem may be worn by members only. 

BY-LAW IX 
PUBLICATIONS 

SECTION 1. All matters of general interest deemed worthy of permanent record 
shall be published in serial volumes as soon as possible after each regularly called 
members' meeting. A copy shall be mailed each member in good standing to his 
last address of record. Extra copies shall be printed for general distribution, and 
may be obtained from the Secretary on the payment of a fee fixed by the Board 
of Governors. 

BY-LAW X 
LOCAL SECTIONS 

SECTION 1. Sections of the Society may be authorized in any state or locality 
where the Active membership exceeds 20. The geographic boundaries of each 
section shall be determined by the Board of Governors. 

Upon written petition, signed by 20 or more Active Members, for the authoriza- 
tion of a Section of the Society, the Board of Governors may grant such authoriza- 
tion. 

MEETINGS 

SECTION 2. The regular meetings of a Section shall be held in such places and 
at such hours as the members may have designated at the preceding meeting. 

The Secretary-Treasurer of each section shall forward to the Secretary of the 
General Society, not later than five days after a meeting of a Section, a statement 
of the attendance and of the business transacted. 

OFFICERS 

SECTION 3. Each Section shall nominate and elect a Chairman, two managers, 
and a Secretary -Treasurer. The Section Chairmen shall automatically become 
members of the Board of Governors of the General Society, and continue in that 
position for the duration of their terms as Chairmen of the Local Sections. 

ELECTION OF OFFICERS 

SECTION 4. The officers of a Section shall be elected to their respective offices 
at the Annual fall meeting of the Section, by a majority of autographed ballots 
of the membership of the Section, and counted by a Committee of Tellers ap- 
pointed by the Section's Chairman. 



July, 1930] CONSTITUTION AND BY-LAWS 141 

All Section officers shall hold office for one year or until their successors are 
chosen, except the Board of Managers, as hereinafter provided. 

MANAGERS 

SECTION 5. The Board of Managers shall consist of the Section Chairman, the 
Section Past Chairman, the Section Secretary-Treasurer and two Active Members, 
one of which last named shall be elected for a two year term, and one for one year, 
and then one for two years each year thereafter. At the discretion of the Board of 
Governors and with their written approval this list of officers may be extended. 

BUSINESS 

SECTION 6. The business of a Section shall be conducted by the Board of Man- 
agers. 

EXPENSES 

SECTION 7. (a) As early as possible in the fiscal year, the Secretary of each 
Section shall submit to the Board of Governors of the Society, a budget of ex- 
penses for the year. 

(6) The Treasurer of the General Society may deposit with each Section 
Secretary-Treasurer, a sum of money, the amount to be fixed by the Board of 
Governors, for current expenses. 

(c) The Secretary-Treasurer of each Section shall send monthly to the Trea- 
surer of the General Society, an itemized account of all expenditures during the 
preceding month. 

(d) Other expenses than those enumerated in the budget, as approved by the 
Board of Governors of the General Society, to be payable from the funds of the 
General Society, must first be authorized by the Board of Governors. 

(e) A Section Board of Managers may authorize, and shall provide for the 
payment of local assessments or any expenses of a Section beyond those authorized 
to be paid from the general fund of the Society. 

(f) The Secretary of the Society shall, unless otherwise arranged, supply to 
each Section all stationery and printing necessary for the conduct of its business. 

PAPERS 

SECTION 8. Papers shall be approved by the Section's Papers Committee pre- 
vious to their being presented before a Section. Manuscripts of papers presented 
before a Section, together with a report of the discussions, and the proceedings 
of the Section meetings, shall be forwarded promptly by the Section Secretary- 
Treasurer to the Secretary of the General Society. Such material may, at the 
discretion of the Journal Committee of the General Society, be printed in the 
Society's publications. 

MEMBERSHIP 

SECTION 9. Should the Active membership of a Section fall below 20, or the 
average attendance at meetings not warrant the expense of maintaining the or- 
ganization, the Board of Governors may cancel its authorization. 

SECTION 10. All members of the Society of Motion Picture Engineers in good 
standing residing in that portion of any country set apart by the Board of Gov- 
ernors tributary to any local Section, shall be considered members of that local 



142 CONSTITUTION AND BY-LAWS [J. S. M. p. E. 

Section, and shall be so enrolled and they shall be entitled to all privileges that 
such local Section may, under the General Society's Constitution and By-Laws, 
provide. 

CONSTITUTION AND BY-LAWS 

SECTION 11. Sections shall abide by the Constitution and by By-Laws of the 
Society, and conform to the regulations of the Board of Governors. The conduct 
of Sections shall always be in conformity with the general policy of the Society as 
fixed by the Board of Governors. 

BY-LAW XI 
AMENDMENTS 

These By-Laws may be amended at any regular meeting of the Society by a two- 
thirds vote by ballot of the members present at the meeting, a quorum being pres- 
ent, either on the recommendation of the Board of Governors or by a recommenda- 
tion to the Board of Governors signed by ten Active Members. 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 



LOYD A. JONES, EDITOR pro Urn. 



Volume XV AUGUST, 1930 Number 2 

CONTENTS 

Page 
Some Aspects of the National Electrical Code as Applied to the 

Motion Picture Industry JAC. R. MANHEIMER 145 

Report of Standards and Nomenclature Committee 160 

Some Considerations in the Design of Sound- Proof Camera 

Housings L. E. CLARK 165 

Some Experiments in Motion Photography of the Vocal Cords . . 

G. OSCAR RUSSELL AND CLIFTON TUTTLE 171 

A Proposed New Method of "Timing" Negatives 

M. W. PALMER AND A. J. RICHARDS 181 

A Comparative Study of Sound on Disk and Film 

PORTER H. EVANS 185 

Some Experiments in Medical Motion Pictures in Color 

HARRIS B. TUTTLE 193 
Apparatus for the Analysis of Photographic Sound Records .... 

OTTO SANDVIK 201 
Progress in Industrial and Scientific Cinematography in France. 

MARCEL ABRIBAT 214 

Applied and Scientific Cinematography in Austria 

PAUL SCHROTT 223 

Abstracts 237 

Book Reviews 241 

Officers 242 

Committees 243 

Presidential Address 246 

The Banquet 250 

New York Section 273 

Chicago Section 273 

The New Constitution and By-Laws 274 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 



G. L. CHANIER 
O. M. GLUNT 
A. C. HARDY 


Associate Editors 

P. MOLE 
W. B. RAYTON 
P. K. SABINE 


S, E. SHEPPARD 
J. L. SPENCB 
L. T. TROI.AND 



Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
Editorial Office, 343 State St., Rochester, N. Y. 



Copyrighted, 1930, by the Society of Motion Picture Engineers 



Subscription to non-members $12.00 per year; single copies $1.50. Order from 
the Secretary of the Society of Motion Picture Engineers, 20th and Northampton 
Sts., Easton, Pa., or 2 Clearneld Ave., Bloomfield, N. J. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Application pending for second-class entry at the Post Office at Easton, Pa. 



SOME ASPECTS OF THE NATIONAL ELECTRICAL CODE AS 
APPLIED TO THE MOTION PICTURE INDUSTRY 

JAC. R. MANHEIMER* 

Recent fires both in the East and in the West have more than ever 
attracted the attention of the various fire underwriters and fire pre- 
vention bureaus to the necessity of formulating rigid and definite 
requirements in connection with the vast amount of electrical work 
now being installed or contemplated in the studios, laboratories, film 
exchanges, and theaters. 

The writer hopes, through this paper, to provoke sufficient discus- 
sion at this meeting to disclose any technical data regarding the ex- 
plosiveness of gases given off by film, especially in view of the state- 
ments made by some writers that nitrocellulose film is not explosive. 

It is not the purpose of this paper to discuss the chemistry of film 
nor the fire hazards attendant to the handling of it, but it cannot help 
but bring forth features which are relevant and important to some 
features of electric work, which have heretofore been uncertain. 

The object of the Electric Code as recommended by the National 
Fire Protection Association is to provide definite requirements for 
the installation and subsequent safe operation of electric circuits, 
conduit systems, distribution centers, and electrical equipment in 
general in various types of buildings. 

The development, however, of the motion picture art has been so 
rapid, especially the electrical phase, that the Code has been unable 
to keep pace with it. This is partly due to the fact that the Electrical 
Code Committee revises the Code only every second year. 

The Code Committee works by subdividing and parcelling out to 
several subcommittees the various sections of the Code, and these 
committees turn in their reports to the committee chairman previous 
to the biannual meeting which usually takes place in February. The 
changes and additions are adopted or rejected by the full committee 

* E-J Electric Installation Co., New York City. (Read before the Society at 
Washington.) 

145 



146 JAC. R. MANH^IMER [J. S. M. p. E. 

at this meeting, and such changes and additions as are accepted are 
embodied in the next issue of the National Electric Code. 

CONFLICTS WITH PRESENT CODE 

The majority of our membership is generally familiar with many 
of the requirements of the National Electric Code applying to the 
motion picture industry; but few realize that if some requirements 
contained in the present Code were enforced, the. development and 
expansion of the art would suffer considerably. Several items are 
ambiguously covered by the Code or are in conflict with it. For ex- 
ample, Section 503w reads, " Wires of different systems shall not oc- 
cupy the same conduit." This is explained by a fine print note which 
states, "Different systems are those which derive their supply from 
(1) different sources of current, (2) transformers connected to separate 
primary circuits, or (3) transformers having different secondary 
voltages." While the ruling speaks of conduit only, it is interpreted 
to mean metal enclosures of all kinds, such as cutout boxes, race- 
ways, troughs, and ducts. 

In many systems of sound recording and reproduction, the a.c. 
street service is supplied to the motors which drive d.c. generators 
on motor generator sets. The generators usually furnish 12 volts 
for filament supply, 250 volts for grid bias, and as high as 1000 volts 
for plate potential. The circuits supplying these various voltages are 
grouped at the amplifying boards and in the amplifying tubes them- 
selves. 

There are also systems where different voltages are supplied from 
batteries which are in turn charged by either motor generators or 
rectifiers. 

The question at once arises as to whether, under the Section 503w, 
these wires can be installed in the same conduits. 

SOUND RECORDING INSTALLATIONS VS. ELECTRICAL CODE 

The question of Code requirements is probably more complex in 
the studio at this time than in any other division of the indus- 
try. 

Section 503g of the Code limits the number of wires in a conduit 
or a duct to those given in a schedule under this section. This causes 
mechanical conflict at amplifying boards, horns, motor patch panels, 
and at other pieces of apparatus where thousands of wires from all 
parts of the building may terminate at one location. 



Aug., 1930] ASPECTS OF NATIONAL ELECTRICAL CODE 147 

For example, in the Western Electric Company's electrical inter- 
locking recording system; the energy which operates the various 
synchronous devices is obtained from a special motor generator as- 
sembly known as a "distributor." The generator of this device func- 
tions as a phase changer since it has impressed upon it the house sup- 
ply of 220 volts, 3-phase, 60 cycle current, and in operation the phases 
are shifted so that the output voltage is approximately the same as 
the input at 3-phase but about 30 degrees phase difference. The 
distorted output supplies fractional horsepower motors on the various 
cameras and recording equipment in the studio at approximately 220 
volts, 3-phase. The motor driving this phase changer is energized 
from a 110 volt d.c. supply which is the output of a I 1 /* kw. motor 
generator set. The motor on the 1V 2 kw. motor generator set is 
supplied by the 3-phase, 220 volt house current. The armature 
winding of the distributor motor is tapped at two opposite points 
through slip rings. By this means, 20 cycle a.c. at approximately 
27 volts, is delivered for special speed control. This 20 cycle a.c. 
is passed through a small transformer and then through a rectifier 
tube for furnishing rectified plate current (d.c.) back into a special 
control field on the same motor for regulating its speed. 

The same rectified a.c. is also transmitted to various "starting 
stations" on the studio stages to give visual indications on d.c. 
milliammeters of the amount of current in milliamperes flowing in 
the control field stated above. 

A d.c. series field is also provided on the driving motor of the dis- 
tributor to give extra torque for "starting duty" only, but is auto- 
matically taken out of circuit when the motor reaches full speed. 

The rotor of the distributor motor is equipped with a small inductor 
generator which delivers a.c. at a frequency of approximately 720 
cycles and 130 volts and supplies energy through a filter which in 
combination with a rectifier tube furnishes the energizing current to 
the control field stated above.* 

The camera and recording motors each have a rotor and stator 
with independent windings. The stators are supplied from the 3- 
phase, 220 volt house current and the rotors from the distorted phase 
supply output of the distributor. The rotor current has the same 

* In the theater projection booth, similar combinations having different volt- 
ages and different characteristics obtain with the Western Electric driving motor 
unit and speed control on projectors so that we have nearly the same problems, 
as far as the Code requirements are concerned, although of a lesser magnitude. 



148 JAC. R. MANHEIMER [J. S. M. P. B. 

voltage and characteristics as the house current except for its angular 
phase displacement effected by the distributor. 

From the distributor, a set of six wires is run to an interconnection 
panel, known in recording parlance as a patch panel. In addition to 
these six wires, there are two more wires for the rectified milliammeter 
current following the same route. Six wires are run between the 
patch panels and each fractional horsepower motor; eleven addi- 
tional wires between the patch panel and each starting station. 

Six wires running to the fractional horsepower motors are all 
a.c. 

Two wires connect to the indicating d.c. milliammeters (rec- 
tified a.c.). 

Three wires connect to a special 3-phase, 220 volt rheostat 
located at the motor station. 

Six wires run to starting stations and are used for actuating 
solenoids, starting relays, and signals through momentary con- 
tact push buttons. 

From the brief description of only the circuits involving the inter- 
locking distributor system, it is readily seen how complex the conduit 
system would be if strict adherence to Section 503w of the Code were 
enforced. 

In connection with the battery supply, "B" battery energy is 
usually furnished by the same set of batteries at 350 and 130 volts. 
These batteries are charged from the 1Y 2 kw., 120 volt d.c. motor 
generator mentioned above, the driving motor of which, as already 
stated, is connected to the 3-phase, 220 volt house supply. 

The "A" battery supply of 6 volts is obtained from one high 
capacity set of storage batteries and the 12 volt "A" battery supply 
from another high capacity set. Both sets are charged by a combina- 
tion 7 l /z 15 volt special d.c. motor generator set, the driving motor 
of which is also connected to the 3-phase, 220 volt house supply. 
On the stages themselves, microphone junction boxes are installed 
which contain a 130 volt local dry "B" battery connected to the 
microphone amplifier. A 6 volt "A" battery supply is also brought 
to this same terminal point as well as six pairs of No. 19 twisted lead- 
covered conductors which run to the monitoring room for microphone 
output. At these junction boxes, the multiple point pin plug re- 
ceptacles provided are arranged with a ground connection for the 
continuous electrostatic shielding and grounding. 

These descriptions of interconnected electrical systems of various 



Aug., 1930 1 ASPECTS OF NATIONAL ELECTRICAL CODE 149 

voltages and characteristics are not given as a treatise on the elec- 
trical circuits of sound recording, for this is neither the scope of this 
paper nor a task which the writer is prepared to undertake, but are 
given merely to indicate the complexity of the many problems which 
the Code Committee must work out. 

NEW CODE REQUIREMENTS FOR SOUND RECORDING AND REPRODUCTION 

SYSTEMS 

In order to provide all the safety possible and at the same time to 
permit reasonable methods to be used which will not hinder nor inter- 
fere with development and progress in this branch of the art, a 
subcommittee of the National Fire Protection Association has been 
delegated to work out this problem and will submit to the Electrical 
Committee which meets in February, 1931, the following recom- 
mendations dealing with sound recording and reproduction for in- 
clusion as rules in the next issue of the National Electric Code: 

3502 (a) Automatic overload protective devices shall be provided in accord- 
ance with the requirements of Article 8 of this Code. The smallest practical 
rating or adjustment with which the apparatus will operate should preferably be 
used. Circuits to supply "B" or "C" voltage shall be protected by automatic 
overload protective devices rated at not more than 1 ampere. 

(6) Wires may be grouped in the same conduit, armored cable, metal raceway, 
pull box, junction box, or flexible cord, types K, S, or SJ between receptacles and 
loud speakers or camera booths, under conditions as noted in sub-paragraphs 1 
to 5 below, provided all wires have insulation rated for the maximum voltage 
applied to any wire. In no case shall the insulation requirements be less than that 
for 600 volts. 

1. Wires emanating from the same piece of apparatus and/or terminating 
in the same piece of apparatus. 

2. Wires that carry current from a primary source which is used to drive 
a motor whose speed is electrically controlled, or to drive a group of motors 
operating in synchronism may be run in the same conduit, etc., with wires 
that carry other currents of characteristics differing from the characteristics 
of the primary current, required for the operation and /or synchronization of 
a motor or group of motors. 

3. Wires to loud speaker fields and armatures, also from receptacles to 
camera booths provided that when receptacles and plugs are used they shall 
be of polarized type. 

4. Wires from the projector sound head and/or turntable to amplifier 
equipment. 

5. Wires to supply "A," "B," and "C" voltage from motor generators 
and batteries provided they are protected by automatic overload protective 
devices installed at the nearest accessible point to the batteries or generators. 
(c) Input leads to a motor generator or to a rotary converter shall be run 

separately from wires emanating therefrom. 



150 JAC. R. MANHEIMER [J. S. M. p. E. 

(d) Storage batteries shall be installed in accordance with proposed require- 
ments of revised Article 18. 

(e) Insulation of wires exposed to oil or oil dripping shall be of a type ap- 
proved for interior wiring that will not be injured by oil or shall be protected from 
such injury by a seamless metallic covering over the insulation. 

(/) The number of wires in any one conduit shall be limited by Section 5Q3q, 
Table 3.* That for metal trough raceway shall comply with Table 3, allowing 
40 per cent of area for conductors. 

(g) Wires terminating in groups at patch panels or similar connection boards 
shall be covered with a single wrapping of asbestos tape or equivalent material 
over convenient groups. This is not required where the metallic covering is 
carried to within 6 inches of the terminals. 

(h) Wires to or from "A" batteries shall be run in conduit or duct compart- 
ments and separated from all other wires, unless all wires and cables in the same 
conduit or duct are sheathed with lead or other approved shielding. 

() All metal trough raceways shall be of not less than No. 14 B. S. sheet metal 
gauge. They shall have ample strength and rigidity in order that they will keep 
their shape. Seams, corners, back edges, and splices in sheet metal shall be 
flanged or lapped over, unless made of continuous weld, or they may be butt 
jointed if reenforced by flat iron strips of same thickness of metal as that of race- 
way. Seams shall not show open cracks when finished and before the raceway 
or ducts are painted or enameled. Covers shall be of same gauge metal as race- 
way and secured to raceway by machine screws spaced not more than 1 foot 
apart. If raceway is placed in floor and has cover flush with the surface, covers 
of at least */4 in. steel must be used. 

Metal trough raceway may be installed in concealed space if run in a straight 
line between outlet or junction boxes. Covers of boxes must be accessible. 
Edges of metal must be rounded at outlet or junction boxes, and all rough pro- 
jections smoothed to prevent abrasion of insulation or conductors. Raceways 
made up of sections shall contain a ground conductor to which each section shall 
be bonded and grounded as prescribed by Article 9. 

PROPOSED REVISION OF ARTICLE 18 N. E. CODE (STORAGE BATTERIES) 

1801 General 

(a) The provisions of this article are intended to apply to all stationary in- 
stallations of storage batteries consisting of a number of cells connected in series 
with a nominal potential in excess of 16 volts and connected for service where so 
installed. 

(6) Wiring and appliances supplied with current from such storage battery 
installations shall be subject to the general requirements of this Code applying to 
wiring and appliances fed from generators developing the same difference of po- 
tential. 
1802 Battery Room 

(a) Provision shall be made for a sufficient diffusion of the gases from the 

* Schedule giving maximum number of wires permitted in conduit for "stage 
pocket, border circuits and elsewhere by special permission" now also applies to 
recording installations. 



Aug., 1930] ASPECTS OF NATIONAL ELECTRICAL CODE 151 

battery to prevent the accumulation of an explosive mixture in the battery room. 
(NoTB: Normally, natural means of ventilation are sufficient. The closed closet 
type of battery installation shall not be permitted.) 

(ft) Wiring shall be enclosed in non-corrodible or suitably protected conduit 
system, or shall be exposed and installed in accordance with the requirements of 
Section 501 of this Code, except that in battery rooms varnished cloth or tape 
insulated conductors shall not be permitted, and except that bare conductors 
may be used in the battery room when properly supported. Where metallic 
conduit or covering is used in the battery room, at least 12 in. of the conductor 
at the end connected to cell terminal shall be free from such metallic conduit or 
covering, and the end of the conduit or covering shall be sealed tightly to resist 
the entrance of acid or acid fumes. 
1803 Batteries not over 250 volts (nominal) potential 

(a) Cells in series circuit not over 250 volts shall be subject to the following 
provisions for additional insulation. 

(ft) Cells in lead-lined wood tanks, not over 50 volts series circuit, shall be 
supported individually on glass or glazed porcelain insulators; over 50 volts, on 
oil insulators. 

(c) Cells in jars made of conducting material shall be installed in trays of 
non-conducting material supported on glass or glazed porcelain insulators, with 
not over 16 volts in series circuit in any one such tray. 

(d) Cells in unsealed jars made of non-conducting material shall be assembled 
in trays supported on glass or glazed porcelain insulators ; or, when installed on a 
rack, shall be supported in groups on glass or other insulating members. 

(e) Cells in sealed rubber or composition jars, assembled in wood trays, shall 
have such trays supported on glass or other approved insulators. 

(/) Cells in sealed rubber or composition containers, without wood trays, 
shall require no additional insulation when not over 150 volts in series circuit; 
when over 150 volts, shall be installed in trays or on racks with not over 150 
volts in series circuit, each such tray or rack to be supported on glass or glazed 
porcelain insulators. 

(g) Cells in sealed glass jars, either with or without wood trays, shall require 
no additional insulation. 
1804 Batteries over 250 volts (nominal) potential 

(a) Cells, of any type, in series circuit of over 250 volts, shall be subject to the 
provisions of Section 1803, and in addition shall be installed in trays or on racks 
supported on oil insulators, in groups of not over 250 volts in series circuit in each 
such insulated tray or rack; except where oil insulators are specified in Section 
1803 for cells in series circuit of less than 250 volts; and excepting that cells of 
not over 10 ampere-hour capacity in sealed glass jars may be grouped in trays 
with not more than 250 volts in series circuit, each such tray to be supported on 
glass or glazed porcelain insulators, the trays being mounted on racks supported 
on oil insulators with not over 500 volts in series circuit on each such insulated 
rack. (NOTE: Maximum protection is secured by sectionalizing high voltage 
batteries into cell groups insulated from each other.) 
1805 Racks and Trays 

(a) Racks, as specified in this article, refer to either (1) wood racks coated 
with an acid resisting material; or, (2) metallic racks coated with acid resisting 



152 JAC. R. MANHKIMER [J. S. M. p. E. 

material and provided with non-conducting members for the support of the bat- 
tery. 

(6) Trays, as specified, refer to crates or trays made of wood or other non- 
conducting material, and when not of glass, rubber, or composition shall be coated 
with acid resisting material. 

There are still a great many more items in the studio, laboratory, 
and theater for which the present National Electric Code does not 
make adequate provision and with which the Code Committee is 
greatly concerned. 

GROUNDING AND SPECIAL ATTACHMENT PLUGS 

The Labor Department of the State of New Jersey now requires a 
third or additional grounding conductor on all portable cables, cords, 
and polarity plugs, and receptacles for grounding portable equipment. 
This feature is now required on all film printing apparatus used in the 
film laboratories in New York City. 

There has been considerable discussion resulting in special local 
requirements in which the use of the ordinary attachment plug and 
receptacle is prohibited in locations where film is handled. 

In New York territory, the local inspection departments are re- 
quiring the use of a plug and receptacle device where the arc estab- 
lished by the pulling out of a plug is confined to the inside of the re- 
ceptacle before the pins of the plug are completely withdrawn, thereby 
eliminating the possibility of igniting a piece of film which might be 
in proximity with such a plug and receptacle. This has been ac- 
complished in various ways. One is to enclose the complete recep- 
tacle and plug in a cabinet with a self-closing cover slotted to permit 
the cord to pass through. When the plug is pulled out of the recep- 
tacle, the cover is still closed. Another device is designed with a 
metallic skirt deep enough to permit the pins of the plug breaking 
contact while the pins are still completely enclosed. As far as the 
writer knows, the matter is still being discussed by the Code Commit- 
tees and some standard construction for these devices will probably 
be incorporated in its February, 1931, report. 

VAPOR PROOF FIXTURES 

The question of vapor proof fixtures in buildings where film is 
handled is well known to most of us. Most of the local inspection de- 
partments are requesting the use of vapor proof fixtures not only in 
film vaults but also in rooms where film is worked, as well as in corri- 



Aug., 1930] ASPECTS OF NATIONAL ELECTRICAL CODE 153 

dors leading to such rooms. This applies equally to rooms in which 
sound film recording machinery is located. 

There seems to be considerable difference of opinion regarding the 
real necessity for vapor proof fixtures. One inspection department 
in New York requires vapor proof fixtures but will also accept the 
use of a metal dish under the lamp when located in film working 
rooms; in other words, a fixture similar to the totally indirect unit. 
This is merely a precaution to catch the hot filament of a broken 
lamp and prevent its dropping upon and igniting film. 

If this practice is sound, the problem of properly lighting film work 
rooms is not a serious one as many commercial type fixtures can be 
obtained in this form. However, if the use of vapor proof fixtures 
is enforced in all locations, the problem of good lighting will assume 
a more complicated and expensive form. 

New local rules in New York prohibit the use of chain fixtures with 
cords laced in and out of the rings, or drop cords in rooms where film is 
handled. All such units must have the fixture wires properly enclosed 
in a metal pipe stem. This applies as well to Wratten safelight units 
which heretofore were connected by means of a flexible cord into a 
lamp receptacle located at some convenient point near the safelight. 

The question has been raised regarding the use of wall switches in 
rooms where film is handled. The Code now prohibits the use of 
switches in vaults but serious thought is also being given to the ad- 
visability of requiring the use of vapor proof type switches in all 
rooms where film is handled. 

Attention is also being given to the use of wall fans in similar 
locations, especially of the types with commutators and with rheo- 
stats in the bases. 

To definitely establish in the minds of the Code Committee whether 
there is a necessity for such devices will depend largely on a definite 
conclusion regarding the combustibility or explosiveness of the 
gases which are given off by motion picture film under ordinary 
conditions. These facts can best be obtained from the membership 
of our own Society, and any discussions or suggestions offered by you 
will be gladly received and considered by the Code Committee of the 
National Fire Protection Association. 

EXIT AND EMERGENCY LIGHTS 

Another section of the Code that is receiving the attention of the 
Code Committee deals with the matter of emergency lighting. Sev- 



154 JAC. R. MANHSIMER [J. S. M. P. E. 

eral sound recording studios and laboratories are being cut up into 
comparatively small areas for use as stages, recording rooms, battery 
and generator rooms, film-working rooms, inspection rooms, etc. 
Many of these are placed in the interior of large buildings and fre- 
quently below the street level. In case of failure of the electric cur- 
rent which might or might not take place at the same time as a fire, 
an unfailing supply of current for emergency and exit lighting is a 
most important consideration. Therefore, it has been recommended 
that an independent source of supply for these lights be provided, 
preferably of the "Surelite" type, in which a storage battery of suf- 
ficient capacity to maintain the emergency lights for at least a half 
hour is automatically kept charged at the proper voltage but is not 
left floating on the line. 

In systems of this type, the emergency lighting is automatically 
thrown on to the emergency battery supply in case of failure of the 
normal current supply. 

This system of emergency lighting is compulsory for theaters in 
many states. 

As an adjunct to the emergency lighting for dark rooms in film 
laboratories, I wish to call to your attention a very simple pilot light 
device originated by Mr. J. C. Kroesen of the Fox Film Corporation 
and first used, I believe in their plant. This consists of a small red 
or green pilot light being placed on each group of key switches which 
operate the white lights. These pilot lights burn continuously and 
not only assist the laboratory operators in inserting the key to turn 
on the white lights, but also provide a permanent indicator to enable 
the white light switches to be quickly located in case of emergency. 
The local inspection departments have commended this type of con- 
struction and it very likely will be incorporated in the new Code. 

SILENCING SIGNALS FOR SOUND STAGES 

Another problem created in the studio is that of locking the doors 
leading to stages to prevent disturbance while recording is going on. 
The fire departments in most cities frown upon locking of exits in any 
type of building. In the eastern studios of the Paramount-Publix 
Corporation, Mr. M. W. Palmer, Chief Engineer, has had placed near 
the outside of each door leading into the various stages, an electrically 
illuminated translucent sign which indicates very forcibly when re- 
cording is going on. These signs have backs coated with a mercury 
compound so that when not illuminated they give the appearance 



Aug., 1930] ASPECTS OP NATIONAL ELECTRICAL CODE 155 

of a mirror. However, when recording is to take place, a monitor 
at a central point operates switches which light the signs on the doors 
of stages on which recording is taking place, and at the same time 
announce in bold letters the word "SILENCE" operated by a flasher. 

PORTABLE CABLES 

The question of portable cables as used in the studio has been the 
subject of considerable discussion by the Code Committee. Certain 
local boards have objected to large amounts of energy being conveyed 
by portable cables to portable spider boxes for the reason that the 
cables are subject to mechanical injury from scenery, wheel trucks, 
etc., and in the event of a short circuit taking place, the heavy capac- 
ity fuse used permits sufficient energy to pass to maintain a serious 
arc. Very frequently, these same fuses are reenforced, especially 
when they are of the renewable type, so that the hazard is even 
greater. 

The consensus of opinion of members of the Code Committee work- 
ing on this section has been that portable cables should not be fused 
for more than 150 amperes on each side of a two-, three-, or four-wire 
system and should terminate in portable pockets raised clear of the 
floor rather than in spider boxes; these portable pockets to be con- 
structed in the form of a small enclosed "location" switchboard pro- 
vided with magnetic contactors and control switches, if desired, so 
that the lights can be controlled remotely. However, the question of 
maximum allowable carrying capacities on portable cables is still 
an open one ; and the Code Committee, being mindful of the expan- 
sion and development taking place in studio illumination, wants to 
consider this question with all regard to the requirements of the in- 
dustry, but at the same time minimizing the electrical fire hazard in 
the handling and maintenance of heavy current equipment. 

THEATER WIRING 

The use of three-wire branch circuits in commercial building is per- 
mitted by the Code but since all present dimmer installations are being 
made so that the dimmers are connected into the neutral or grounded 
leg, the Code Committee is now considering prohibiting the use of 
three-wire circuits in any theaters or auditoriums where dimmers are 
to be installed. 

Past experience has indicated that contractors and wiremen are 
misled by the fact that the neutral leg of a three-wire circuit carries 



156 JAC. R. MANHEIMER [J. S. M. p. E. 

no current when the circuit is evenly balanced; but in installations 
where dimmers are connected into the neutral, the so-called three- 
wire circuit does not and cannot exist. What has really occurred is 
that the installation man has used a common return for two two-wire 
circuits, usually of the same size wire as the outside circuit legs ; ob- 
viously twice as much current is carried by this common return as 
the remaining leg of either circuit, producing an overload on this one 
wire which is not a neutral of a three-wire circuit. There would 
be no objection to running a wire of twice the capacity for a common 
return, but the surer method would be to enforce the use of two- wire 
circuits entirely for installations of this kind. Neutral wires should 
terminate in the magazine panel, and be connected to separate ter- 
minals opposite the live terminals of the corresponding circuits and 
not to common grounding busses as is customary in commercial in- 
stallations. By arranging the connection terminals thus, the elec- 
trical inspector can, at a glance, check whether the circuits have been 
run as two-wire circuits, especially when one of them is a grounded 
conductor. 

The conductor leading to the dimmer plate should have a capacity 
equal to the sum total of the capacities of the various two-wire cir- 
cuits. A common ground bus is now frequently used to tie together 
all common terminals of the dimmer plates. 

Switchboard manufacturers should pay more attention to the 
routing and grouping of bus bars and branch feeders so that opposite 
polarities on a.c. systems are always together. The contractor 
likewise should exercise caution in the running of wires in the gutter 
spaces and between the magazine panels and the switchboard or dim- 
mers so that wires of opposite polarities are always grouped through 
bushings, conduits, or other metallic ducts. Where this practice is 
not carefully observed considerable "a.c. hum," inductive and eddy 
current heating of the conductors and iron is produced, with conse- 
quent damage to the installation. 

CONCLUSION 

Technical developments frequently involve changes in methods 
that may not be covered by the current Code or may be infractions 
of it. 

It is the purpose of the National Electric Code to provide safety but 
not to hamper development. Therefore, when such conflicts arise, 
it is advisable to bring these promptly to the attention of the local 



Aug., 1930] ASPECTS OF NATIONAL ELECTRICAL CODE 157 

Inspection Bureau for a temporary ruling until suitable provision 
can be inserted in the National Electric Code. Any precautions 
adopted that will safeguard property and insure the safety of the 
employees and the public will redound to the credit of the industry. 

DISCUSSION 

MR. SAMUELS: In the case of motor generator sets operating with arcs, we 
have been frequently confronted with a situation where a motor generator op- 
erating on 200 amperes continuously and 400 amperes for the change-over in- 
terval of ten or fifteen minutes, had feeders installed for only 200 amperes. 
Motor generators for projection are distinguished for their flat voltage char- 
acteristics. This use of cables too small for the load causes a considerable voltage 
drop and defeats the purpose for which the equipment is designed. We have 
found several cases in the last six months where the inspector has passed a 200 
ampere cable running to the booth from a 400 ampere machine. What I would 
like to know is, what provision is being made by the Code to enforce the installa- 
tion of the proper size conductors for d.c. feeds to booths? 

MR. MANHEIMER: In connection with motor generator d.c. feeds to booths, 
the inspectors usually are concerned only with the size of the feeder in so far as the 
fuses which protect it are concerned. If a feeder requires 400 amperes momentary 
carrying capacity, it is up to the customer to insist that the contractor install 
cables of such size as will safely carry this amount of current. In a new theater 
the wiring is installed long before the motor generator sets arrive, and it has been 
frequently found that when the sizes of projection feeders are specified, they are of 
insufficient size for the total output of the larger motor generator sets which so 
many theaters are now installing. 

The inspector, in passing on a motor generator installation, usually checks the 
size of the a.c. feeder to see if it is large enough according to the a.c. motor name 
plate rating. On the d.c. end, he is principally concerned with the sizes of the 
fuses that protect the outgoing d.c. feeder, and if these fuses do not exceed the 
capacity of the feeder, the job is passed. After the inspector leaves the job, 
however, it is a simple matter, by the use of refillable fuses, to insert additional 
links having capacities two or three times greater. This is a most unfortunate 
condition which only frequent re-inspection can eliminate. It would, therefore, 
seem advisable that the inspectors on their periodic visits to the theaters check 
the fuses on d.c. motor generator feeds. 

Many of the chain theater construction departments now specify wire no smaller 
than 500,000 circular mils for the d.c. booth feeders. These have a capacity of 
400 amperes per leg, and are usually large enough to carry two projection machine 
arcs and one stereopticon or spotlight simultaneously. 

MR. R. C. HUBBARD: In connection with the matter of switches and fixtures 
in film handling rooms, Mr. Manheimer solicits information regarding the ex- 
plosive gases given off by film. I think we should go on record with the fact that 
no explosive gases are given off by film until it becomes heated to abnormal tem- 
peratures and that there is, therefore, no necessity for vapor proof fixtures in 
film handling rooms. 

MR. MANHEIMER: I should like that particular point settled at this meeting, 



158 JAC. R. MANHEIMUR [J. S. M. p. E. 

if possible, so that the Code Committee can be guided to some extent as to 
whether the requirements for vapor proof fixtures in film working rooms should 
be adopted or not. 

MR. ROBIN: In line with Mr. Manheimer's paper, I found throughout the 
country many violations, and also found variations in frequencies and low volt- 
ages on the d.c. service on motor generator installations. In the majority of 
cases, voltage drop in lines has not been considered, and there is a general lack of 
proper protective devices. I have studied and interpreted the Code for theatrical 
motion picture installations for our different offices, and I have found many 
conflicts between the different inspection departments and the utilities companies 
as to the correct interpretation of the Code. I believe it would be well for this 
Society to appoint a committee to confer with the various underwriters with the 
object of assisting them in the promulgation of rules which will not put too great 
a burden on our industry. 

MR. MANHEIMER: I believe it would be advisable to formulate some special 
rules for the installation of d.c. booth feeders in theaters, on a basis of the prob- 
able sizes of the motor generator sets contemplated. This requirement could be 
worked out probably on a basis comparable with the number of seats in a theater, 
which would indirectly determine the amount of current required by the projection 
arcs. This question should receive some very serious consideration. Both the 
discussions of Mr. Samuels and Mr. Robin are appropriate at this time and the 
conditions pointed out by them are a great deal worse than our membership 
realizes, due to a large extent to the highly competitive basis on which work of this 
kind is usually done and the free-for-all method of letting each bidder write his 
own specifications. 

The Society could render a great service to the industry if it would adopt 
and recommend specifications for installations of this kind so that architects or 
theater owners would merely have to specify, "All in accordance with S. M. P. E. 
Standards," in a manner similar to the standards and specifications adopted by 
other engineering societies and frequently referred to by manufacturers. To 
formulate such standards, a committee should be appointed. 

PRESIDENT CRABTREE: Who is drawing up these underwriters' regulations? 

MR. MANHEIMER: The various Code Committees. 

PRESIDENT CRABTREE: Are they collaborating with men having motion pic- 
ture experience? 

MR. MANHEIMER: Yes, they are, but only to a limited extent. 

PRESIDENT CRABTREE : Do you think a committee from our Society necessary? 

MR. MANHEIMER : In order for a committee from our Society to be repre- 
sented on the Electric Code Committee, it will first be necessary for the Society 
to apply for membership in the National Fire Protection Association, the cost of 
which is very nominal, and representatives will then be appointed from our own 
membership by the National Fire Protection Association, to be represented on the 
various Code Committees in which our Society may be interested. This is the 
procedure followed by the various engineering and technical societies requiring 
representation in the National Fire Protection Association. I am quite sure that 
the Association will not only appoint representatives on the Electrical Committee 
but will probably appoint representatives on committees considering film and 
other branches of fire hazards incident to the industry. 



Aug., 1930 J ASPECTS OF NATIONAL ELECTRICAL CODE 150 

PRESIDENT CRABTREB: If you will leave that to me and the Board of Gov- 
ernors, we will cooperate to the best of our ability. 

DR. SEASB (Communicated): In connection with that part of Mr. Manheimer's 
paper that seems to solicit some definite information regarding the explosiveness 
of gases given off by film, I consider that the vapors in a film vault of average size 
filled with film under average conditions will not be explosive or combustible. 
The vapor to be found is largely acetone. The acetone in the film may be as high 
as 2 per cent. It is usually much less. This acetone is very hard to remove and 
would require quite high temperatures to get it out of the film. According to 
our information, vapors of acetone are not explosive until the acetone content 
of the ah- is 3.7 Ibs. per 1000 cubic feet. We have no information on the accumula- 
tion of vapors in a vault which has remained closed a long time, but it is possible 
that the vapors may increase if the vault is practically hermetically sealed. 

We know of no spontaneous combustion of vapors from film, nor have we had 
in our experience any fire caused by the ignition of vapors emanating from film. 
There are records of fires having been caused by static discharges over mixers 
into which solvents were being run. 

While the vapor from film is largely acetone there is some alcohol, camphor, 
and fusel oil. These vapors have higher specific gravity than air, and, therefore, 
tend to settle. 

It is possible that the vapor proof globe requirements have been established 
to reduce the hazard of igniting film by its contact with an incandescent lamp. 
Celluloid film ignites in a very short time at 300 F. At 212 F. it will not ignite 
for a considerable time. At 140 F. we have observed its decomposition without 
ignition in five or six months. 



REPORT OF STANDARDS AND NOMENCLATURE 
COMMITTEE* 



The present Committee on Standards and Nomenclature was 
organized during January of this year, and the first meeting was held 
in New York City on January 27th. All members of the Committee 
were present at that time except the representatives from France and 
the West Coast. A second meeting was held in New York on April 
14th and was likewise well attended. Undoubtedly one reason for 
the excellent attendance at these meetings is the greater opportunity 
of service to the Society which the new method of adopting standards 
provides. Whereas as much as two years might elapse under the 
old method before the recommendations of this Committee could 
be adopted by the Society, the new method permits the adoption by 
letter ballots, which are sent all regular members of the Society im- 
mediately following the appearance of the report in the JOURNAL. 

The work that this Committee is undertaking at present may be 
summarized under the following headings: Preparation of Booklet, 
Nomenclature, Safety Code for Projection, Standard Practice, and 
Wide Film Dimensions. 

PREPARATION OF BOOKLET 

The booklet giving the standards adopted by the S. M. P. B. to 
January, 1928, is now out of print. The board of governors has re- 
cently authorized the preparation and publication of a new booklet 
which will include also the standards adopted by the Society since 
January, 1928. The editor pro tern of the JOURNAL, Mr. L. A. Jones, 
has kindly assumed the responsibility for publication of this booklet 
and a few copies have been struck off. The Chairman of this Com- 
mittee is taking the necessary steps to obtain the approval of the 
American Engineering Standards Committee, and it is hoped that 
the booklets will be available for distribution within a short time. 

NOMENCLATURE 

A subcommittee, consisting of Messrs. Carson, Dubray, Powers, 

* Presented at the Washington meeting of the S. M. P. E., May 6, 1930. 
160 



REPORT OF STANDARDS COMMITTEE 161 

and Rayton, Chairman, has been appointed to make such revisions 
in the glossary of technical terms as may be necessary from time to 
time. It is planned to print the revised glossary in the JOURNAL every 
year, preferably after the Fall meeting of the Society. Wherever 
possible, the foreign equivalents of the terms in the glossary will be 
included also. This should be a welcome addition, as these terms are 
seldom found in the dictionaries of foreign languages. 

SAFETY CODE FOR PROJECTION 

Most states and important municipalities have enacted regulations 
governing the projection of motion pictures, but these differ widely 
from place to place. It is felt that this lack of uniformity creates an 
unnecessary hazard. As matters stand at present, the projectionist 
must often learn an entirely new code whenever he moves from one 
city or state to another. Undoubtedly, the approval of a standard 
safety code for projection by an impartial body like this Society would 
provide a basis for new legislation which would tend to become stand- 
ardized as time went on. To this end, a subcommittee is being or- 
ganized to deal with this important problem and to report at a later 
meeting. 

STANDARD PRACTICE 

Although motion picture practice is constantly changing, certain 
details of the art tend to become standardized; and it is felt by this 
Committee that the publication of the details of recommended prac- 
tice should be of benefit to the industry. A subcommittee has been 
organized, consisting of Messrs. Farnham, Hubbard, Mitchell, and 
Rackett, Chairman, which will present and publish recommendations 
on the length of titles, notching of negative film, sound film practice, 
and such other features of the art as it may seem wise to attempt to 
standardize. It is hoped that a report of this subcommittee will be 
available in time to be presented at the Fall meeting of the Society. 

WIDE FILM DIMENSIONS 

The Committee felt that the standardization of wide film dimen- 
sions was the problem of prime importance before it, and this subject 
was discussed at considerable length at the meeting of January 27th. 
The points under discussion were treated in the following manner, 
which seemed to afford a logical approach to the subject: 

1. Is a larger screen desirable and can it be used in existing theaters? 



162 REPORT OF STANDARDS COMMITTEE [J. $ M. "p. E. 

2. Should the angle of view be increased in other words, should 
the screen include more action than at present? 

3. Can a larger screen be used with the present 35 mm. film? 

4. What is the best ratio of width to height of the screen? 

5. Is a wider sound track desirable? 

6. What detailed film dimensions should the Committee recom- 
mend to the Society? 

The Committee agreed unanimously, and experience has un- 
doubtedly proved that a large screen is desirable and that it can be 
used in practically all existing theaters. The Committee also agreed 
that the enlargement of the screen should be accompanied by an in- 
crease in the camera angle so that more action will be included. In 
other words, the focal lengths of both the camera lens and the projec- 
tion lens should remain about the same as at present. The wider 
film then automatically includes a larger camera angle and covers a 
larger screen without destroying the perspective relations, which are 
approximately correct with the present 35 mm. film. Although an 
increase in film size requires both the camera lens and the projection 
lens to cover a wider field angle, the Committee believes that there 
is evidence to show that the optical manufacturers can deal with this 
problem satisfactorily. 

The Committee feels that it is impracticable to cover a larger screen 
with existing 35 mm. film since the magnification of the film on the 
screen is now about as great as can be tolerated without exceeding 
the limit at which the graininess becomes decidedly objectionable. 
At the present time, no method of reducing the graininess of photo- 
graphic materials is known that does not entail a sacrifice of speed or 
sensitivity. The use of materials of lower sensitivity would introduce 
greater difficulties in the lighting of studios and does not appear to 
be a thoroughly practical solution of the problem. It has often been 
demonstrated (notably by J. H. Powrie, Trans. Soc. Mot. Pict. Eng., 
No. 19 (1924), p. 49) that the graininess of the positive can be mark- 
edly decreased by printing by reduction from a larger negative. 
Thus, if graininess were the only factor, it might be possible to cover 
a much larger screen with 35 mm. positive film by increasing the size 
of the negative film only. However, the increased magnification re- 
quired by the larger screen accentuates any unsteadiness of the film in 
the gate, and introduces some severe mechanical problems. With the 
increasing use of color films, it seems undesirable to contemplate any 
greater magnification between the film and the screen than at present 



Aug., 1930] REPORT OP STANDARDS COMMITTEE 163 

and a slightly lower magnification is to be preferred. Also, the 
amount of light flux passing through the film is already so great that 
only with difficulty could it be increased to meet the requirements of 
the larger screen. 

The ratio of width to height of the screen was discussed by the 
Committee at considerable length. It was felt that the best ratio 
depends upon the type of subject and that the old 4:3 ratio was not 
far from the best compromise. With the advent of sound films, the 
picture has become more nearly square, and it is quite generally 
agreed that this change was in the wrong direction. As the height of 
the screen can be increased only slightly in most theaters, any great 
increase in the size of the screen must be in the width. The Commit- 
tee feels that the proper ratio can be determined only after compara- 
tive tests, and is arranging for a demonstration to which the producers 
will be invited. 

At the time of the January meeting of this Committee, it was ap- 
parent that the entire Standards Committee was too large to under- 
take the problem of wide film standardization. Consequently, a 
subcommittee was appointed consisting of Messrs. Batsel, Chair- 
man, Davee, DeForest, Evans, Griffin, LaPorte, Spence, and Spon- 
able. This committee has worked faithfully on the problem and has 
held no less than seven meetings since February 13th. Every possible 
phase of the subject has been examined exhaustively, with the 
result that it now appears that there is little to choose from an en- 
gineering standpoint between the present 65 and 70 mm. layouts. It 
is thought that the 65 mm. film would be somewhat improved if the 
margins between the exposed areas were increased, and the 70 mm. 
film would doubtless be improved by the use of five perforations per 
frame instead of four. 

As soon as it became apparent that the problem was no longer an 
engineering one, a second meeting of the entire committee was called 
on April 14th, which resulted in a resolution that the Chairman 
should interview the producers and acquaint them with the situation 
and propose that the producers agree to pool the cost of scrapping 
existing equipment where necessary in order that the industry may 
promptly arrive at a common standard for wide film. 

Pursuant to these instructions, the Chairman called on Mr. H. L. 
Clarke, G.T.E. Fox; Mr. A. Zukor, Paramount-Famous-Lasky 
Corporation; Mr. H. M. Warner, Warner Bros.; and Mr. H. Brown, 
R.K.O. Mr. I,. P. Mayer is in California, and a letter has been di- 



164 



REPORT OF STANDARDS COMMITTEE 



reeled to him there. The Chairman is pleased to report a general 
desire to do whatever is best for the industry and a feeling that the 
matter of standards can safely be left to this Committee. 

We regret that we are unable to put a specific recommendation be- 
fore you, due to insufficient time to arrive at an agreement on all 
points under consideration. However, work on this problem will 
be continued and an early report on this subject is anticipated. 



M. C. BATSEL 
W. H. CARSON 
L. W. DAVEE 
A. DEBRIE 



J. A. DUBRAY 
E. W. BNGSTROM 
P. H. EVANS 



R. K. FARNHAM 
H. GRIFFIN 
R. C. HUBBARD 
L. A. JONES 
N. M. LAPORTE 
G. A. MITCHELL 
W. P. POWERS 
G. F. RACKETT 



Respectfully submitted, 

W. B. RAYTON 
V. B. SEASE 
T. E. SHEA 
J. L. SPENCE 
E. I. SPONABLE 
L. T. TROLAND 
A. C. HARDY, 
Chairman 



SOME CONSIDERATIONS IN THE DESIGN OF SOUND- 
PROOF CAMERA HOUSINGS 

L. E. CLARK* 

The fundamental requirement of a silent cover "bungalow," 
or "blimp," as it is colloquially called is that the device shall effec- 
tually keep the camera noise from getting out on the set. In general, 
it can be said that any device which lets camera noise be heard by a 
person of normal hearing standing more than four feet from the 
camera in an absolutely silent room, is not sufficiently quiet to cover 
all conditions. This is the fundamental consideration; all others, 
while they may be of major importance, are secondary to this. Some 
of the other requirements are: 

(1) Accessibility of the Camera. Doors should be provided which 
are large enough and in such places that they readily permit the 
operator to get at all parts of his camera. For a Mitchell camera, 
for example, it is imperative that the operator be able to get at the 
back, the left side, and the front of his camera. There are certain 
adjustments which he has to make on the right side of his camera 
as well, but if a large door is provided in the back, it will be sufficient 
to cover this need. These doors should be readily opened and when 
fastened should make solid and airtight joints. 

(2) Freedom from Changes in the Camera. The successful photog- 
raphy of a feature production is in itself so much of a strain on a 
cameraman that he is in no condition to have imposed upon him 
added difficulties caused by changes in his camera necessitated by 
the blimp. For example, the relative location of finder and camera 
aperture should be maintained as at present. Furthermore, his 
elaborate mat box and filter holders should be kept as they are 
now so that he will be able to get any photographic effects he 
desires. Plenty of room around these should be provided for a 
man to work and make adjustments. The mounting of the camera 
in the blimp should be the same as at present, and the blimp 

* Pathe Studios, Inc., Culver City, California. (Read before the Society at 
Washington.) 

165 



166 



L. E. CLARK 



[J. S. M. P. E. 



should place no restrictions upon the lenses which the cameraman 
can use. 

(3) Ease of Camera Operation. All the controls which it is possible 
to bring outside the blimp should be so arranged, the most indispen- 
sable, of course, being the follow focus control. Next in importance 
comes the control of the lateral adjustment of the camera finder 
to permit accurate centering on travel shots. It is also desirous 

to provide control for auto- 
matic fade-ins and fade- 
outs, although fewer of 
these are being used than 
was formerly the case in 
silent pictures. The 
motor control, of course, 
should be provided with 
necessary safety means 
whereby the motor is in- 
stantly shut off in the 
event that the camera 
becomes j ammed . A very 
important set of controls 
is that governing the aim- 
ing of the camera that is, 
the panning and tilting 
arrangement. These 
should not only be pro- 
vided with gear move- 
FIG. 1. 







Side view of blimp and tripod blimp 
closed. 



ments, but provision 
should also be made for 
releasing the gear drive to 

permit the operation of the camera and blimp as if it were on a uni- 
versal joint. Control is then obtained by means of a lever large 
enough to permit proper handling of the entire blimp and camera 
head. 

With these requirements in view, the Academy of Motion Picture 
Arts and Sciences made a survey of the existing camera bungalows, 
which were in use, and found that none of them were quiet enough to 
fill the prime requisite as specified in the beginning of this article. 
On the other hand, practically none of them permitted all the other 
requirements being fulfilled either, so that the devices were in the 



Aug., 1930] 



SOUND-PROOF CAMERA HOUSINGS 



167 



nature of compromises, some of which were better than others. The 
best devices, from a sound standpoint, were all large and heavy, 
ranging in weight from 180 pounds to 225 pounds. For each of these 
blimps, also, a special tripod had been constructed to properly handle 
the extra weight, and it was more or less agreed that this sort of 
construction would have to be resorted to in order to provide a de- 
vice adequate to fill all requirements. 

With the results of this 
investigation, which were 
made public to anyone 
interested in the subject, 
it was a relatively simple 
matter to combine the 
good points and to design 
a set of equipment which 
seems to completely fill 
the requirements. In the 
first place, from a studio 
operation standpoint, such 
equipment should be de- 
signed to be interchange- 
able and more or less stand- 
ard. Furthermore, pro- 
vision must be made to 
cover all cases in which a 
blimp would be likely to 
be used. 

The first point that p IG . 2 . Front view of blimp and tripod blimp 
was noted was that a closed, 

blimp suitable from a 

sound standpoint would be so heavy that it would be impossible to 
properly operate it on any of the commercial existing tripods. The 
writer, accordingly, in connection with Mole-Richardson, Inc., of 
Hollywood, set out to design a complete line of tripod equipment 
to properly support a blimp of necessary weight. The details of 
this tripod are being presented to the organization in another paper, 
but the main feature from an operation standpoint is that a com- 
plete set of equipment is provided. Two heights of adjustable tripod 
and a set of castings known as "high hats" to permit the camera 
being placed even lower than the lowest tripod, have been designed 




168 L. B. CLARK [J. s. M. P. E. 

and tested. A specially designed extra heavy tilt head, which is 
interchangeable on any of the tripods or on any of the blimps, has 
also been developed. With the design and construction of this line 
of equipment in the hands of Mole-Richardson Company, attention 
was next turned to the design of a sound-proof blimp. 

After several experiments, the present design was decided upon, 
which produces ample quieting and at the same time is very con- 
venient for operation. The body of the blimp is built around two 
sets of angle iron frames. The inner set is covered with Vi 6 in. 
sheet lead which is primarily responsible for any added sound proofing 
which the blimp may have. An aluminum shell is built around the 
second angle iron frame, the two frames being so designed that the 
lead slips inside the aluminum shell with a 3 / 4 in, space all around. 
This space is filled with Johns-Manville "Akoustikos" felt. This 
provides a very rigid shell. The inside of the lead is lined with 
another 3 / 4 in. of "Akoustikos" felt, and the felt surface is finished 
on the inside with black Kribble cloth, to provide a clean working 
surface inside the blimp. By use of the angle iron frame, the whole 
device is provided with enough rigidity so that the doors when once 
fitted, will always remain tight fitting and will not develop leaks 
at some later date. The side door and the back door are built of 
the same laminated construction as mentioned above, except that a 
flat frame instead of an angle iron frame is provided. The door 
jambs are of sponge rubber so that at the corners of the blimp a 
rubber to rubber seal about 2 L /2 in. through is provided at all joints. 
By means of special compression hooks which have been designed, 
the rubber surfaces are jammed together practically airtight. Inci- 
dentally, the problem of obtaining suitable compression hooks was 
quite difficult. Nothing even remotely resembling what was de- 
sired could be purchased, and the hooks had to be designed from the 
ground up. The resulting job provides a 3 /4 in. pull with a mechani- 
cal advantage of about 16 to 1, so that a 50 pound pull on the handle 
produces a compression equivalent to 800 pounds on the rubber 
surfaces. 

The camera shoots through optical glass, this glass being fitted 
in a door which raises up to permit the cameraman to get at the 
front of his camera to adjust mats, filters, and other accessories. 
The front of the blimp is flared and extends out about six inches 
further than the body to permit the use of the mat box and very 
short focal length lenses. The blimp will clear a 25 millimeter lens 



Aug., 1930] 



SOUND- PROOF CAMERA HOUSINGS 



169 



with ease. This flare on the front of the blimp is also large enough 
to let the finder be used directly on the camera in its usual manner, 
and a window is provided in the back door so that the cameraman 
can look through his finder while the blimp is in operation. 

Considerable trouble was experienced in getting a proper mount- 
ing for the camera. Most of them were either too rigid, allowing 
too much noise to be telegraphed to the outside, or if they were 
silent, so flexible that the 
camera wobbled back and 
forth whenever the blimp 
was panned. The present 
mounting eliminates these 
difficulties and is one of 
the major features of the 
blimp. A large aluminum 
casing, practically the en- 
tire base of the blimp in 
size, is laid on the felt floor 
of the blimp. This has a 
large enough area so that 
it has no tendency to 
wobble even under severe 
conditions. To this plate 
is screwed a shock-proof 
mounting consisting of 
alternate triangular 
shaped pieces of balsa 
wood with sponge rubber FlG 3 Side view of blimp and tripod-blimp 
between, and a cast alu- open showing camera in position, 

minum plate, top and 

bottom, the whole mounting being held together with strips of live 
rubber. A camera screw is provided in the top plate of this mount- 
ing which is identical with the camera screw existing in the standard 
Mitchell tripod so that the camera is mounted in its usual man- 
ner. 

This covers the general design of the blimp and its more impor- 
tant features. The cameras are provided with automatic trips 
which close an electric circuit connecting to a circuit breaker the 
instant that even a slight buckle forms in the camera. These have 
saved the camera from serious injury many times. The motor 




170 L. E. CLARK 

control and circuit breaker are mounted in a single unit on the out- 
side of each blimp. 

For following focus, which is one of the most important features 
of the camera, several devices are in use. The simplest and most 
fool-proof provides merely an adjusting ring which clamps around 
the lens in use and which has an extension arm to which a rod, pass- 
ing up through the bottom of the blimp, is attached. A window in 
the side door and a suitable flash light inside the blimp permit watch- 
ing the graduation on the lens barrel when the focus is being changed 
by means of the external rod. This device, although admittedly 
crude and simple, has the merit that the operator is constantly 
watching the calibration on the lens itself and not a secondary cali- 
bration somewhere outside the blimp. 

Another control which has been provided is a similar rod operat- 
ing out through the side door which connects with a pin on the finder 
permitting the finder to be moved laterally so as to keep the proper 
frame of the picture. Where pictures are being shot with the idea 
of making both full size prints and prints masked for sound track, 
the accurate alignment of the picture becomes a subject of prime im- 
portance, at least if an artistic result is desired. 

The present blimp which is now in operation at Pathe Studios, 
Inc., Culver City, together with the tripod as designed and built 
by Mole-Richardson, Inc., seems to fulfill most of the requirements 
which can be laid down. While it is, of course, more difficult to use 
than when shooting with an open camera, yet it imposes less restric- 
tions upon the cameraman than most of the blimps that have gen- 
erally been in use. From a sound standpoint it is amply quiet, it 
being possible to record whispering within three feet of the blimp 
without picking up any noise from the camera whatsoever. 

The writer wishes to express his acknowledgment of the whole- 
hearted cooperation of everyone working on this problem. Especially 
the names of Peter Mole, Elmer Richardson, and Philip Coates, 
all of Mole-Richardson, Inc., and Joseph Wright, A. L. Domike, 
and Ferol Redd, of Pathe Studios, should be mentioned. Thanks 
are also due to the Academy of Motion Picture Arts and Sciences 
for the results of their investigation of this problem. 



SOME EXPERIMENTS IN MOTION PHOTOGRAPHY OF THE 

VOCAL CORDS 

G. OSCAR RUSSELL* AND CLIFTON TUTTLE** 

It has been pointed out by one of us 1 that many of the commonly 
accepted theories regarding the mechanism of speech production are 
erroneous. Heretofore, visual observation of the laryngeal cavity 
by means of special instruments supported by the evidence of X-ray 
pictures during phonation has been utilized in these studies. In the 



THVROIP 

CARTlLMbEL 



CARTILAC* 

OF 
WRISBELR& 




TUBCRCL-El OR 
CUSHION OF EPIGUOTT\5 



VOCAL. CORPS 

OR. VOCAU 

WE.PGELS 

VELHTRACULNR 
BANP OR. 

FAUSE VOCAL. 
CORP 

AR.YT ENOVP 
CAR.-nL.AOE. 




ARYT ENOIP 
ELPGE. 

OF 
E.P1OL.OTTIS 



FIG. 1. Two views of the cavity of the larynx. 

present paper we describe a new method of approach, a method which, 
when it is perfected, promises to be most valuable both in the con- 
tinuance of the studies and in the presentation of findings to an audi- 
ence. The motion pictures which have thus far been made, though 
their photographic quality is in no wise as good as we believe we 
can obtain, nevertheless indicate clearly the possibilities of the 
method. 

Successful photography of the vocal cords previous to the attempt 
we describe has been accomplished by others 2 ' 3 but these results have 
been achieved with long exposures of the order of one-half second. 

* Phonetics Laboratories, Ohio State University, Columbus, Ohio. 
** Research Laboratories, Eastman Kodak Co. (Read before the Society at 
Washington.) 

171 



172 



G. O. RUSSBUJ, AND C. 



[J. S. M. p. E. 



The Problem. The vocal cords and the surrounding anatomical 
region which is of particular interest in the study of speech mecha- 
nism occupy a circular area about 5.5 cm. in diameter in the mid-por- 
tion of the larynx. A and B of Fig. 1 are drawings after laryngo- 
periscopic photographs of the cavity of the larynx. 3 The dotted 
circles inscribe the area to be photographed. A shows the full length 
of the cords (about 20 mm.). These are a pearly white in color 
while the surrounding areas vary from a cream pink to deeper shades 




L-TJ-B 

FIG. 2. Cross-section view showing extreme positions of the vocal cords. 

of red. The false cords, which are a darker red than the true cords, 
lie approximately parallel to the latter. B shows the same area as 
it is covered with the epiglottis a smooth, yellowish pink membra- 
nous material slightly concave forward and upward. Physiologically, 
the epiglottis was formerly thought to be a kind of trap door or lid 
which closed down tightly over the larynx during the act of swallow- 
ing. The present experiments show that in this subject the actual 
laryngeal closure is first created by an approximation between the 



Aug., 1930] MOTION PHOTOGRAPHY OF VOCAL CORDS 173 

pulvinar (or cushion) at its base, and the cartilages of Wrisberg in 
posterior-anterior direction ; second, by the ventricular wedges (or 
false cords) laterally. These four points come together in such tight 
constriction as to prevent entrance of even liquids into the interior 
larynx below. The tip of the epiglottis then moves back apparently 
to facilitate posterior movement of the pulvinar, but evidently not 
downward in such a manner as to close the opening. A cough, clear- 




FIG. 3. Cross-section view showing instrument in place for photography. 

ing the throat, or gagging, are all also accomplished by this four- 
point approximation. 

The position of the vocal cord assembly varies from a distance of 
about 60 mm. to perhaps 100 mm. down the throat during the act of 
speaking or singing. The two extreme positions are indicated in 
Fig. 2, in which the vocal cavity is outlined from an X-ray photograph. 
A is the highest position of the cords and B the lowest. The distance 
of a point, C, at the back of the throat, from D at the front of the 
mouth is about 90 mm. 

An optical system to image this inaccessible region upon the film 
in the motion picture camera presents some rather formidable dif- 



174 G. O. RUSSEU, AND C. TUTTUS [J. S. M. P. E. 

ficulties. Nature has provided a nicely balanced set of reflexes to 
prevent the accidental introduction of hard material into the throat 
passages. The average subject will automatically protest an optical 
system thrust into the throat just as energetically as he will an in- 
advertently swallowed bone. 

An unpracticed subject finds it very difficult to accommodate him- 
self to any apparatus in his mouth and extending to the back of the 
throat, but even a subject who has a tendency to gag can, with some 
practice, tolerate a small tube if it is of the proper shape. We have 
designed a periscopic lens system (tube diameter 5 mm.) with high 
light gathering power (geometrical aperture //4) which can be used 
without impeding the articulation of even the consonants, including 
both point and back lingual occlusives and fricatives. 

Experimental Technic. In these preliminary experiments, we have 
used the Russell "Fonofaryngoskop" made by the Electro-Surgical 
Instrument Co. of Rochester. This device consists essentially of 
a tube 135 mm. long and about 13 mm. inside diameter. At either 
end are mirrors which may be tilted with respect to the axis of the 
tube, thus enabling one to view his own layrnx. The use of this device 
in our experiments is illustrated in Fig. 3. The Fonofaryngoskop 
permits clear articulation of all vowels, though the i ("ee" as in 
peep) loses somewhat in brilliancy. Since the view is obtained 
through this small tube, there is no need of forcing the subject to 
open his mouth to the uttermost limit in order to pass in the light, 
forcibly depress the tongue, or pull it out so as to prevent the epi- 
glottis from retracting and shutting off the view of the cords, as was 
formerly necessary in the usage of the old laryngoscopic mirror and 
illuminating device. Obviously no normal speech or voice could 
be produced under such circumstances. The Fonofaryngoskop per- 
mits a naturalness not heretofore possible for the tongue is left abso- 
lutely free to move without any depressing or other extraneous force 
or interference with its accustomed vowel and singing movements. 
It is impossible for the tongue ever to get in the way and shut off the 
view of the cords. Its tube is kept about the same diameter as that 
required of the front buccal cavity in order to pronounce a clear and 
unmistakable vowel i ("ee" as in peep}. Sounding this vowel on 
unstrained high pitches automatically distends the back throat cavity 
and interior larynx over the vocal cords to the utmost, and brings the 
tip of the epiglottis well forward, whereas the vowel a (ah) closes 
the throat in the neighborhood of the epiglottis tip, and automatically 



Aug., 1930] MOTION PHOTOGRAPHY OF VOCAL CORDS 175 

demands what doctors call a "retracted epiglottis." In these experi- 
ments our use of the Fonofaryngoskop permitted us to induce nature 
to yield the best view through psychological persuasion instead of 
force. 

Optical Limitations Imposed by the Fonofaryngoskop. Since the 
inside diameter of the tube is only 13 mm. and since the amount of 
illumination which can be supplied to the area to be photographed is 
limited, the use of a lens of high relative aperture is required. If 
the diameter of the exit pupil of the lens is greater than 13 mm. it 
will be vignetted by the tube. For these reasons we have used a 
lens of 25 mm. focal length and //1. 9 aperture. With this lens as 
close as possible to the end of the tube, the object distance becomes 
150 mm. and the image distance about 30 mm. The effective aper- 
ture is thus reduced to//2.3. The magnification (0.2X ) is somewhat 
less than could be desired. 




FIG. 4. Bent quartz rod. 

Illumination. It is necessary to supply to the rather inaccessible 
laryngeal cavity an intensity great enough to photograph red tissue 
with a lens working at//2.3 at a taking rate of at least 16 pictures per 
second. Previous experience 4 had indicated that under these condi- 
tions and using panchromatic film, a minimum of about 200 visual 
foot candles of illumination from tungsten at 2900K. would be 
required. 

For visual observation, a small battery operated lamp (about */ 
watt) is provided with the Fonofaryngoskop. This lamp will 
furnish about 12 foot candles on the plane to be photographed an 
intensity which is entirely inadequate for the photography. A 
quartz rod in contact with an external source appeared to be the best 
method of conducting sufficient light to the vocal cords. (Fig. 4.) 

With a straight quartz rod 8 mm. in. diameter in contact with the 



176 



G. O. RUSSBLL AND C. TUTTLE [J- S. M. P. E. 



bulb of a 6 volt, 18 ampere ribbon filament lamp operated at 2900 K., 
we were able to obtain about 250 visual foot candles on a plane about 
90 mm. from the rod end. It was necessary to bend the rod in two 
places in order to conduct the light from the source to the laryngeal 
cavity. The first bend was necessary in order to make the rod run 
parallel to the tube where the two entered the mouth. The position 
of the camera relative to the end of the instrument makes it impos- 
sible to place the lamp house in a more advantageous position. The 
first bend (A in Fig. 4) amounted to a total deflection of 55 degrees. 
Fortunately it was possible to make this bend with a circular arc 
such that the critical angle for quartz was always exceeded and there 
was no light loss at the bend. The other angle (B in Fig. 4) which 




FIG. 5. Diagrammatic view of camera, instrument, and head of the subject. 



turns the light downward at the back of the throat was necessarily 
so sharp a bend that some of the reflected rays were incident at an 
angle less than the critical angle. A light loss of about 70 per cent 
was the result. Silvering of this elbow did not improve the efficiency 
of the rod. 

In order to obtain sufficient intensity for motion photography of 
the cords it was necessary to overload* the lamp for the short period 
of taking. 

Fig. 5 is a diagrammatic top view of the camera, D; Fonofaryngo- 
skop, A; quartz rod, B; light source, C; and subject's head, E. 

Discussion of Results. Undoubtedly much more can be learned 
from these preliminary pictures through frame to frame inspection 

* NOTE : An increase of one ampere in the current consumption of this lamp is 
approximately equivalent to a doubling of the photographic intensity. The 
filament can be overloaded to 22 amperes for short times without burning out. 



Aug., 1930] MOTION PHOTOGRAPHY OP VOCAL CORDS 



177 



than is possible by projection at 16 frames per second. Figure 6, a 
short section of the film, illustrates the possibilities of this method. 
In a relatively short time of actual picture taking 
we thus far gathered results which will furnish 
material for months of painstaking research before 
the information to be gleaned will be exhausted. 
A few of the conclusions which seem well sub- 
stantiated by inspection of these films may be of 
interest to this Society. 

(1) In normal speech or song there is a regular 
gathering of mucus on the cords which loads them 
unequally, introducing inharmonic components 
and other like effects analogous to those pro- 
duced by unequal loading on vibrating reeds, 
membranes, piano strings, and other vibrating 
media. As is well known the latter may give 
quality effects, which are piercing, screeching, 
nasal, guttural, etc. Many differing voice quali- 
ties may possibly be traced to this manifestation 
rather than any function of the so-called resonators 
above, represented in the throat, mouth, and nose. 

(2) The false cords, contrary to accepted medi- 
cal opinion, 5 play an important part in the speech, 
voice, and physiological functions of the human 
anatomy. It has been stated 5 that the false 
cords are unimportant and that their removal in 
the case of pathologic conditions has no effect 
upon the voice. These pictures show definitely 
that the false cords and whole interior larynx 
are in constant and wondrous play. It is 
evident that cauterization as treatment of the 
false cords, in such a manner that scar tissue is 
produced, should therefore be avoided. 

(3) The cushioning effects of the pulvinar and 
the cartilages of Wrisberg, functioning along with 
the relaxed but approximated false cords, are 
proved by these experiments. They seem to act: 

(a) As a means of mechanically lowering the 

pitch of the vocal tone, once a certain low 

5. ., , , . FIG. 6. Section of 

limit 01 relaxation in the glottal actuators has vocal cord film. 



178 G. O. RUSSELL AND C. Ttmxs [J. S. M. p. E. 

been reached. This is accomplished by a frictional slowing down 
of the surge through an opening between the pulvinar and cartilages 
of Wrisberg, often narrowed in extreme low pitches to a diameter no 
larger than that of a pinhead. 

(b) As a guttural and other similar quality tone creator where 
mucus in this narrow opening is set into vibration. 

(c) As a by-pass filter permitting the escape of only the low-pitched 
partials. This effect results from the extremely soft surfaces sur- 
rounding the opening thus created, its excessively small size, and the 
power of selfelongation in this narrowed soft tube. 

(d) As an attenuator or tone deadening medium. 

(e) As a creator of stage whisper and other similar effects. 

(4) Contraction, with consequent hardening through extreme ten- 
sion of the whole interior larynx from the tip of the epiglottis right 
down, is definitely proved herein. The effect must inevitably be: 

(a) To create accentuation of the high partials with consequent 
variation of the tonal quality, running from the bright, to the brilliant, 
white, tight, strident, piercing, screeching, and tight-choked. Through 
the series, varying modifications of this tension are seen to take place. 
First a complete distension of the entire inner larynx, in both lateral, 
and posterior-anterior direction, for a pleasing bright or brilliant 
quality, with some apparent tendency toward peripheral loading of the 
glottal actuators (or vocal cords) along the laryngeal attached sides, 
and a thinning out of the edges. Through the progressive series one 
then notes a progressive tightening of the ary-epiglottal muscles which 
narrow and tighten the upper part of the laryngeal tube, and the same 
manifestation in the interior membranaceous muscles, and ventricular 
bands. Constriction of the latter leaves but a narrow slit between 
them through which the vocal cord vibration can escape. This narrow 
strip of glottal membrane is thus forced to push up between them pro- 
ducing a resulting cymbal-like slapping together of the free edges, 
or the equivalent to a clarinet or organ reed striking against the hard 
edge of the mouth piece. The effect of these latter is well known. 

(b) To load the cords in such a way as possibly to create the effect 
of by-pass filters and net- works of varying types. 

(c) To change the amount of cord permitted to vibrate, thus raising 
the pitch as this amount is decreased, without any necessity for in- 
creased tension in the vocal actuator itself. 

All of this makes it clearly evident that too little attention has 
heretofore been paid to the manner in which the interior larynx is 



Aug., 1930] MOTION PHOTOGRAPHY OP VOCAL CORDS 179 

capable of altering voice and speech quality, without any intervention 
whatever of the cavities or so-called resonators above. 

Teachers of speech or voice and of the deaf, surgeons and physicians, 
phoneticians, and other speech and voice investigators may be bene- 
fited by the results obtained from motion pictures of the laryngeal 
cavity. To mention a thing of perhaps small importance: The 
doctor who instructs his patient with the time honored phrase, "Now 
open your mouth and say "Ah" may be interested to know that this 
procedure results in the complete closure of the laryngeal cavity, 
whereas i ("ee" in peep) opens it wide. 

We must offer our apologies in presenting before this audience of 
sound motion picture engineers a silent film which cries out for sound 
accompaniment. The addition of synchronized sound, the use of 
higher magnification, and color, and possibly an attempt at super- 
speed pictures are the developments which we should anticipate. 

REFERENCES 

1 RUSSELL, G. OSCAR: "The Mechanism of Speech," /. Acoustical Soc. Amer., 
I, No. 1 (Oct., 1929), p. 83; and other studies of the series under the auspices of 
the Carnegie Corp. and American Academy of Teachers of Singing. 

2 PANCONCELLI-CALCIA, G. : "Natural Color Photography of the Vocal Cords," 
Umschau, 34, No. 5 (Feb. 1, 1930), p. 92. 

'RussBLL, G. OSCAR: "The Vowel," Ohio State Univ. Press, Columbus, 
Ohio (1928). 

4 TuTTLB, CLIFTON AND MORRISON, C. A.: "Some Preliminary Experiments 
in Medical Photography," Trans. Soc. Mot. Pict. Eng., XII, No. 36 (1928), p. 
1027. 

6 CUNNINGHAM, D. J.: "Text-Book of Anatomy," 3rd ed., Wm. Wood & Co., 
New York, N. Y. (1909), p. 966. 

DISCUSSION 

MR. Ross: It seems as if the instrument raises the palate and closes what is 
known as the "head structure." That is, what we call the "head" voice is ab- 
sent. Does that interfere with the true voice? It is possible that this unequal 
loading of the vocal cords is due to physical deficiency of one side. Were these 
photographs taken of just one person? If so, this might have some bearing on 
the fact that the vocal cords seemed unequally loaded. 

MR. TuTTLE: To answer Mr. Ross's questions about the functioning of the 
cords involves more of a knowledge of phonetics than I lay claim to. I believe 

AUTHOR'S NOTE: Since the presentation of this paper at Washington these 
experiments have been continued. Sound records on 35 mm. film have been 
made simultaneously with the pictures and fairly successful Kodacolor pictures 
have been obtained. 



180 G. O. RUSSELL AND C. TUTTLEJ 

I am quoting Professor Russell correctly when I tell you that he has shown rather 
conclusively that the head tones are really of small importance in determining 
voice quality. He has been working with Metropolitan stars in New York and 
making a series of X-ray pictures of their throats. Before starting to sing these 
artists are careful to get their voices in the "right place" in their heads, and each 
one has his own device for doing this. Some of them choose some upper corner of 
the room and sing to this corner. When they have elevated the voice to a suffi- 
cient extent, they are ready to go on with the performance. Professor Russell 
has demonstrated by instruments showing where the vibration comes from that 
the effect of "voice elevation" which singers obtain is psychological rather than 
physical. 

So far, all the pictures were made of Professor Russell's own vocal cords. To 
use this piece of apparatus requires a person of extraordinary experience. Pro- 
fessor Russell hopes to get other subjects who are able to use the instrument, and 
we hope to complete a periscopic lens system so that even those having a tendency 
to gag can tolerate the apparatus in their throats. 

MR. Ross: I don't agree with Professor Russell with regard to the statement 
that the head structure, that is, the portion of the head from which the head tones 
are drawn, is not essential. It is essential to have the palate forward in singing 
head tones. I think you will get all vocalists to agree on this. 



A PROPOSED NEW METHOD OF "TIMING" NEGATIVES 
M. W. PALMER AND A. J. RICHARDS* 

In presenting this paper to you, we are fully conscious of the fact 
that some of the apparatus which will have to be used in connection 
with our idea has not yet reached the final stage of development. 
Thus far, we have produced operative apparatus only, but rapid im- 
provements are being made, and we are assured by those immediately 
concerned that this improved apparatus will be available very shortly. 

I will first explain briefly what is meant by "timing." Everyone 
who has experimented with photography has encountered the prob- 
lem of ' 'timing' ' his negatives. An exposure is made in the camera and 
then developed into a negative. This negative must then be printed, 
or in other words, light must be allowed to pass through it onto a 
sensitized emulsion to produce a positive. The proper amount of 
light to be used for this is determined by trial and error; several 
exposures are made with various light values, and the proper exposure 
is determined in this way, the results of the incorrect exposures 
being thrown away. Exactly the same procedure is followed in 
printing motion picture negatives, with the exception that the nega- 
tives are inspected by a "timer," before printing, and he records his 
best judgment as to the proper value of light which should be used. 
In some cases the judgment of this "timer" proves to be correct, but 
many times it is not, and millions of feet of film have to be reprinted. 
Sometimes a negative has to be printed five or six times, before a 
satisfactory result is obtained. 

Mr. Richards, who is a laboratory man, myself, a studio man, with 
the aid and assistance of Mr. McCoy of the Westinghouse Lamp Com- 
pany have tackled this problem and this paper contains our sugges- 
tions for improvements along this line. 

In studying this problem of "timing," we began at the end and 
worked back to the beginning. We began by studying the screen 

* Paramount-Publix Corporation, Long Island City, New York. (Read before 
the Society at Washington.) 

181 



182 M. W. PALMER AND A. J. RICHARDS [J. S. M. P. E. 

images in the theater. Since it is the object of the picture to give 
the audience the illusion that they are looking at real people on the 
screen, and since the attention of the audience is necessarily concen- 
trated by the nature of the story, on one principal actor, to preserve 
the illusion, it is necessary that that actor should look the same in 
every scene no matter what may be the changes in his surroundings. 
In order to preserve this continuity of appearance throughout the 
picture, what we have called the ''face value" of that actor must be 
maintained the same in all scenes. This "face value" is the actual 
value of light reflected from the screen by the image of the face. 
Starting with this "face value," we then worked back through the 
various stages of positive developing, printing, and negative develop- 
ing to the actual exposure of the negative when the actor appears 
before the camera in the studio and we find that this is the controlling 
factor in the whole situation. It is merely necessary to measure the 
light value on the face of the actor as he appears before the camera, 
and we will have an index to guide us in "timing" the negative. If 
a lot of light is used in taking, the printing light must be strong and 
vice versa. 

We measure this light value by means of a photo-electric cell pho- 
tometer placed alongside of, or in the motion picture camera. We then 
produce, by means of a small lamp within the motion picture camera, 
an exposure strip along the edge of the film which will be an indica- 
tion of the light value on the face of the principal actor in that par- 
ticular scene. This exposure strip can be produced by having a 
small lamp inside the camera focused on the edge of the film, the in- 
tensity of this light being varied according to the reading of the 
photometer, but remaining constant for the duration of the scene. 
This lamp may be so arranged as to produce several density strips of 
known relative value, and thus give an indication of the gamma to 
which the film was developed. After development of the negative, 
we will have a strip of uniform density along the edge of the film which 
will be an index of the light used on the face of the actor in that par- 
ticular scene. 

In the printing machine, a fixed light source and a photo-electric 
cell are arranged on opposite sides of the film, in the same manner as 
the exciter lamp and photo-cell are arranged in the sound reproducing 
system. The amplified output of the photo-cell will control the value 
of the printing light. Thus the scene will be printed with a light 
which will bear a direct relation to the light used in making the pic- 



Aug., 1930] NEW METHOD OF "TIMING" NEGATIVES 183 

ture, and the "face value" will be the same in all prints, thus produc- 
ing a uniform density for the face of the actor as he appears in various 
surroundings on the screen. 

In the case of scenics, light effects, or other special cases, it will only 
be necessary to decide what particular area we desire to print for 
and then to measure the light value at that particular area, and regu- 
late the exposure of the density strip accordingly. 

Ever since the industry began, there has been a conflict between the 
camera man and the laboratory man. In cases where an unsatis- 
factory result has been obtained, each claims that the other is to 
blame. By this method it will be possible for the camera man to 
place on the film an exact indication of the light which he used on 
every scene, and yet it will not hamper the camera man in any way 
in. exercising all the artistry at his command. 

And now a few words as to the application of this system to the 
making of sound records on film. The exciter lamp on the sound 
recorder can be assumed to remain constant during the recording of 
any particular scene, although it does vary from day to day, or hour 
to hour, as is evident from the fact that sound tracks have also to 
be "timed." To produce an automatic means for "timing" the 
printing of sound tracks, we provide in the sound recorder a means 
for diverting a small beam of light from the exciter lamp into the 
camera to produce on the sound track film a density strip regulated 
by the intensity of the exciter lamp in that particular recording. 
This density strip will control the value of the printing light when the 
sound track is printed just as the light was controlled in printing the 
picture. By the use of this system the operator of the sound recorder 
can if he so desires vary the amount of light used in making the den- 
sity strip during the recording of a scene, and thus introduce trick 
photography into the making of the sound track record. 

After a careful study of the whole situation involved in the applica- 
tion of the above principles, we believe it is practical and that it 
constitutes an extension of the better technic which has come about 
with the introduction of sound pictures into the realm of laboratory 
practice. It gives to the camera man, the laboratory man, and the 
projectionist, a new help in bringing to the man in the theater seat 
a better and more satisfying result. 

Patents have been applied for on this method, and a more detailed 
description of the apparatus involved is shown in the patent applica- 
tion. 



184 M. W. PALMER AND A. J. RICHARDS 

A method has been devised for making up a density strip for films, 
which have been " timed" by other methods so that they can be 
printed on machines to which this new device has been adapted. 

DISCUSSION 

PRESIDENT CRABTREE : The method described by Mr. Palmer is very ingen ious, 
but why not adjust the lighting so that the brightness of the actor's face is constant 
in the first place? 

MR. PALMER: Scenes are taken in the studio under so many different con- 
ditions and in the exterior in sunlight that it is not always possble to match the 
light exactly although something might be done in that directiion. 



A COMPARATIVE STUDY OF SOUND ON DISK AND FILM 
PORTER H. EVANS* 

In considering the relative merits of sound-on-disk versus sound- 
on-film, there are a number of factors which must be weighed. The 
advantages and disadvantages of the two methods must be con- 
sidered from a standpoint of sound quality, operation, and cost; and 
each factor must be considered practically as well as theoretically 
because we all know that the indications of theory are not always 
realized in practice. 

In discussing this problem it must be borne in mind that the 
principal difference between the present phenomenal success of 
audible pictures and previous failures has been the superior quality 
of the present sound reproduction. The present success of audible 
pictures is undoubtedly due to comparatively pleasing reproduction 
in the theater which involves a good frequency characteristic and 
exceptionally uniform speed of the recording and reproducing mecha- 
nisms. It follows at once, therefore, that the advantages from a 
quality standpoint are of greater importance than the advantages 
from an operating or cost standpoint, up to the time that both sound- 
on-disk and sound-on-film yield uniformly equal results under 
commercial conditions. 

In the beginning, disk reproduction unquestionably could be relied 
upon to produce better and more consistent results in the theater. 
When Warner Brothers started making audible pictures it was the 
only commercial system available. Prior to this time, several in- 
terests were endeavoring to develop the photographic process of 
recording sound but public demonstrations established the fact that 
this process was not commercial at that time. 

Since that time on frequent occasions, it has been asserted that 
better results can be obtained with sound-on-film than with sound- 
on-disk. This statement is either based on tests made in the labora- 

* Eastern Studios, Warner Brothers Vitaphone Corporation, Brooklyn, N. Y. 
(Read before the Society at Washington.) 

185 



186 PORTER H. EVANS [j. S. M. P. E. 

tory where every step of the recording, developing, printing, and 
reproducing is done by expert engineers or where the disk has been 
made by re-recording from film to disk and, therefore, has in addi- 
tion to its own limitations the limitations of the original film record. 
As will be noted later, we are recording simultaneously on disk and 
film (but releasing only on disk) and at the studio we find little 
choice between the best film reproduction and the average disk 
reproduction. The disk method, however, has the extremely valu- 
able characteristic of being more uniform and reliable than the film 
in the theater. 

Records have been produced commercially for some twenty-five 
years and as a result the galvano and pressing processes have reached 
a high degree of perfection. Experience has been accumulating for 
several years on the use of electric recording equipment and as a 
result the technic of cutting waxes by the electric process is well 
understood and no difficulties are encountered with this part of the 
work. 

From a theoretical standpoint, it would appear that a better fre- 
quency response characteristic should be obtainable by the use of 
sound-on-film than by the use of sound-on-disk because the former 
need not employ to any great extent the use of mechanical vibrating 
systems with their resulting resonant distortions. It would appear 
that an inertialess light beam and an aperiodic photo-electric cell 
should be capable of response to frequencies of higher order of mag- 
nitude than the recording stylus and electrical reproducer used in 
the sound-on-disk method. Laboratory tests seem to substantiate 
this view but this advantage has been lost in the theater up to the 
present time because the other elements in the system are not able 
to handle the frequency range which the sound-on-disk method is 
capable of producing, to say nothing of the increased frequency 
range claimed for the sound-on-film. On the other hand, sound-on- 
disk has the theoretical advantage of more inertia in the moving 
record and is, therefore, less susceptible to irregularities in record 
speed. 

From the practical operating standpoint there are many advantages 
to sound-on-film which were apparent from the very beginning. On 
the other hand, there are many disadvantages which are apparent 
when pointed out, but which were not appreciated until an attempt 
was made to use this method commercially. While the practical 
difficulties which are arising may not be insurmountable, they do give 



Aug., 1930) A STUDY OF SOUND ON DISK AND FILM 187 

the older disk method the advantage until they are solved. The 
obvious advantages of sound-on-film referred to above are so im- 
pressive that the development and perfection of this method of re- 
cording has and still is receiving a great deal of attention with the 
result that noteworthy improvements are being made in this process 
of recording. In order that Warner Brothers might have first-hand 
information on the sound-on-film method, we began recording on 
film, about a year ago and today the majority of our sound is si- 
multaneously recorded on both film and disk. 

In spite of the fact that theory and laboratory tests indicate that 
a better frequency response characteristic should be obtainable on 
film than on disk the reverse has been found to be the case in 
practice. The causes of this condition are gradually being dis- 
covered and eliminated with the result that there is less difference 
between the two methods of recording at the present time than at 
any time heretofore. 

Obviously, there is a marked advantage to the distribution and 
exhibition organizations in having the sound and picture permanently 
associated with each other. The use ' of disk records requires the 
maintenance of two separate exchange organizations one for the 
film and one for the record, and requires two independent shipments 
to the exhibitor with a small increase in shipping expense and twice 
the danger of some one making an error in the shipment. 

Another practical advantage of the film method arises when the 
film is damaged in projection. In the case of the disk print, it is 
essential that the damaged section of film be replaced by a blank 
leader of exactly the same length as the portion removed, otherwise 
synchronism is destroyed. In the case of the film print, the con- 
tinuity of the sound may be lost and some bad splicing noises intro- 
duced but it does not involve any question of synchronism in subse- 
quent sequences. 

To offset the unrealized theoretical advantage of a wider frequency 
response characteristic a great deal of difficulty has been experienced 
in obtaining uniformity in the film product. This unforeseen diffi- 
culty is very important from a practical standpoint. It has been 
necessary to establish tolerances in exposure, development, printing, 
and reproduction which have been difficult and expensive to meet. 
In addition to this, the equipment required to record, print, and re- 
produce the sound record has been found complicated by comparison 
with its disk equivalent and, therefore, difficult to maintain in proper 



188 PORTER H. EVANS [J. S. M. p. E. 

adjustment. On the recording end, the more exacting technic for 
film recording has not been difficult to meet because the film recording 
equipment is in the hands and under the control of experts. In addi- 
tion, the recording equipment is satisfactory from a speed variation 
standpoint. A driven rotating sound gate is used in the recording 
machine which supplies the inertia inherently lacking in the moving 
film. 

Since virtually everything is re-recorded before release, retakes on 
account of cut-overs are very rare, as it is possible to use records in 
re-recording which are cut too heavy to pass commercially. While 
this is a disadvantage for disk it is more than offset by the advan- 
tage that a wax may be played back immediately. 

From an editing standpoint there seems to be little choice between 
the two methods of recording. The vast majority of the release 
sound must be re-recorded in either case. Re-recording can be done 
by either method without any appreciable change in sound quality. 
From the director's standpoint the sound film is very useful. The 
cutter can join up the sound track at the same time he cuts the pic- 
ture. The director can, therefore, judge the length of the waits be- 
tween sequences and the effect of changes of sequences on continuity 
without having to wait for the sound department to re-record the reel, 
and changes in the cutting can be made and reviewed immediately. 
From the sound department's standpoint, however, there is little or 
no advantage to editing with film. Before sound film can be re- 
recorded a matched print should be made. This requires time and, 
in general, delays the re-recording operation. As a result we have 
found that the most practical procedure is to supply the cutters with 
sound track for their use, and when the production has the director's 
approval we make the release records by re-recording from disk. 

In our sound-on-film work we have been extremely fortunate from 
the film laboratory standpoint. Our laboratory has quickly learned 
the use and value of sensitometric control and is capable of producing 
the density and contrast specified within practical operating limits. 
Their greatest difficulty has been in the suppression of ground noises, 
but in this respect the product is thoroughly commercial. 

On the exhibition end, most of the sound heads in use at present 
slide the film past a stationary sound gate with the result that irregu- 
larities in the friction of the film against the gate produce a flutter. 
As a result of film shrinkage, only one pair of teeth in the pulling 
sprocket made contact with the film at one time. At the moment the 



Aug., 1930] A STUDY OF SOUND ON DISK AND FILM 189 

pulling pair of teeth are disengaged from the film a slight slippage of 
the film is required to bring the next pair of teeth in contact with it. 
This results in a speed variation known as sprocket-hole modulation. 
Where a hold-back sprocket is not provided, variations in the tension 
of the takeup mechanism are transmitted directly to the pulling 
sprocket with resulting variations in speed. 

In addition to the difficulties with speed variation in film reproduc- 
tion, the adjustments in the sound head are complicated and exacting. 
There is an exciter lamp which must be placed in exactly the right 
location and supplied with the right current ; an optical system which 
must be accurately adjusted so as to properly focus the light coming 
from the lamp; mechanical guides for the film which must ac- 
curately align the sound track with the sound gate; and a photo- 
electric cell and a two-stage amplifier in which the energy level is ex- 
tremely low which makes the problem of excluding extraneous noises 
such as those caused by electrical induction and mechanical vibration 
very difficult, and consequently makes the ratio of tube and cell 
noise to sound relatively high. 

From the standpoint of the equipment, a disk reproducer is sim- 
plicity itself. The only attention the reproducer requires in the pro- 
jection booth is the insertion of a new needle with each disk. If 
anything goes wrong with the reproducer, a new one may be installed 
quickly, easily, and cheaply. The only skill required on the part of 
of the projectionist is that required to select the correct record and 
place the needle on the start mark, and occasionally replace a section 
of damaged film by the same length of blank leader. A little difficulty 
has been experienced in getting projectionists capable of doing this. 
It is much more difficult to find men who can properly maintain the 
more complicated sound head. 

Another recognized disadvantage of the use of sound-on-film is 
the effect on the shape of the picture rectangle. Many people did 
not like the proportions in the silent pictures, after stealing space for 
the sound track the proportions are worse. 

In comparing sound-on-film with sound-on-disk from a cost stand- 
point, again it must be considered from both the producers' and ex- 
hibitors' viewpoint. From the producers' viewpoint, as pointed out 
above, the disk method involves the cost of the records and the cost 
of the record exchanges this represents quite an item. On the other 
hand, if the addition of sound to the release prints materially shortens 
the life of the release prints, an enormous increase in film cost follows. 



190 PORTER H. EVANS [j. S. M. p. B. 

Very little information is available on the life of the combined sound 
and picture print, and what is available is not reliable because there 
are no established standards for determining when the useful life of 
sound track has been passed. In the beginning, first-run houses did 
not attempt to project a print more than fifty or sixty times. If this 
standard of reproduction were maintained film costs would be in- 
creased four or five times and would more than offset the cost of 
records. At the present time, the life of combined picture and sound 
film appears to vary from 50 to 100 per cent of the life of the pic- 
ture print without the sound the difference depending upon the 
care exercised in handling the film. If the addition of the sound 
track does not reduce the life of the release prints, obviously the sound- 
on-film method is Ijess expensive from the producers' viewpoint. 

On the other hand, when the sound track is placed on the film along- 
side of the picture it is necessary to replace the entire print whenever 
a new sound record is needed. Inasmuch as a thousand foot release 
print costs many times that of a disk it is only natural that there is 
a marked reluctance to retiring a print before it is absolutely neces- 
sary. As a result, sound-on-film is frequently retained in service 
long after it would be desirable from the sound standpoint to retire 
it. With disk recording, additional records are furnished to replace 
the records in service whenever there is a noticeable depreciation 
in the quality of the reproduction. This results in a marked ad- 
vantage to the second- and third-run houses. 

It has been our contention that the superior quality resulting from 
the use of sound-on-disk will increase the theater patronage enough to 
more than offset the increased transportation costs of this method. 
However, it may be desirable at some future date, due to improved 
results obtainable with film, to make sound available by both methods 
and permit the exhibitor to choose the type of sound record he pre- 
fers. Those who have been fortunate in obtaining good film equip- 
ment and those who are unable to detect any difference in box office 
returns between the two methods will undoubtedly elect sound-on- 
film. 

CONCLUSION 

From a theoretical standpoint it would appear that a better fre- 
quency response characteristic can be obtained using photographic 
recording. This theoretical advantage, however, has not as yet 
been realized from a practical standpoint. 



Aug., 1930] A STUDY OF SOUND ON DISK AND F^ILM 191 

We would expect to have less speed variation troubles with sound- 
on-disk, and this advantage has been observed in practice. 

From the handling standpoint, sound-on-film is preferred by the 
exhibitor and distributor. On the other hand the disk method has 
the advantage that the problems of equipment and maintenance in 
the theater are greatly simplified. 

From the standpoint of quality, sound-on-disk has in the past 
given consistently better results because of the greater simplicity of 
the reproducing equipment and the absence of speed variation. As 
theater reproduction of sound-on-film improves this advantage of 
the disk method will gradually disappear. 

From a cost standpoint the sound-on-film is preferred by the ex- 
hibitor who does not take into account the effect of quality on the 
box office returns. 

From the producers' standpoint, the relative cost of the two meth- 
ods depends on the sound film life. At the present time there is 
little choice between the two. As the sound film life is improved by 
more careful handling the cost of this method will decrease. 

In other words sound-on-film appears to have many potential ad- 
vantages which, if realized, should make it superior to sound-on-disk 
but until they are realized in practice we prefer disk. 

DISCUSSION 

MR. CARLTON: May I ask from what standpoint the sound record on film goes 
to pieces? Is it ground noise, or what does limit its life? 

MR. EVANS: Film that is handled in the average way in the theater gets dirt 
and grease on it. This raises the ground noise. If it is handled carelessly in the 
projector or run through projectors that are out of repair, the film tears at the 
sprocket holes. If these tears extend into the sound track the tear produces 
noise. Film life is apparently determined by the amount of ground noise tol- 
erated. 

PRESIDENT CRABTREE : Perhaps the Projection Committee has information on 
that point. I know that Mr. Faulkner of the Paramount organization has in- 
formation on it. Mr. Coffman says he will mention this in a paper later. 

MR. BRAUN: Has Mr. Evans figures on the preferences of the exhibitors of 
motion pictures? I think such a statement might be most illuminating. 

MR. EVANS: I have no figures. If one talks to the exhibitors some prefer one 
and some the other. If the exhibitor prefers disk, it is because he is particular 
about the quality of his reproduction. If he prefers film it is because he worries 
about the handling and shipping problems. This man generally is not critical of 
sound quality. In our theaters, they run both, and when they have a disk job 
they take an evening off and enjoy themselves. 

MR. MAXFIELD : I think first that this paper is one of the most comprehensive 



192 PORTER H. KVANS 

and, to my mind, unbiased attempts to analyze the differences between film and 
disk records that I have heard. My experience in Hollywood was limited to pro- 
ducers releasing most of their material on film. Two producers record important 
musical selections on disks, and if they dub it on film they dub from the disks 
because they get a cleaner production in the loud passages in the disk method than 
on the film. When they have to dub from film they compound the film defects. 
They are therefore recording their heavy numbers on disks and re-recording to 
disks for disk releases and to film for film releases. 

MR. COFFMAN : During these discussions it might be wise to keep in mind what 
one of the speakers termed the "subjective factors" affecting the judgment of 
sound quality. Several papers on semi-controversial subjects have been pre- 
sented here today, and the discussions seem to indicate that most individuals 
tend to develop a strong bias in favor of the method or equipment with which they 
are most familiar. In my own case, I find that nowhere does reproduction sound 
so generally satisfactory as in my own projection room. It is no better than many 
places elsewhere, of course, and it is undoubtedly poorer than may be found in 
some of the best projection rooms. Our own bias may sometimes lead us into 
false interpretations of the most accurate data, even when our intentions are 
most sincere. The ear seems to develop habits very much more easily than our 
other sense organs, so let us be on guard when we invoke its assistance in arriving 
at important decisions. 

PRESIDENT CRABTREE : In case the sound is recorded on a separate film, would 
there be any greater handling difficulties than when handling disk records? 

MR. EVANS : I should think the problems would be greater. The sound film 
would have more bulk and weight and would be much more expensive than 
the record. It is subject to the same handling problems that disk records are. 
From a sound quality standpoint, it is open to the objection that nobody has been 
able to develop and construct a sound head as simple as the magnetic pickup for a 
record. The only advantages I see for it are that it could be shipped in the 
same package with the picture film and it would eliminate retracking troubles 
but from every other point of view it would be less desirable than the disk 
record. 

In connection with Mr. Coffman's remarks, I know what he means. It is very 
difficult to keep an open mind on these things. Our sound film generally comes 
from the laboratory before the disks come in. When I listen to it without disk 
for comparison I sometimes think it is entirely satisfactory, but later on when 
we run it against the disk on a blindfold test, invariably the observers pick the 
disk because it is firmer and clearer and contains more detail than the film. 



SOME EXPERIMENTS IN MEDICAL MOTION PICTURES IN 

COLOR 

HARRIS B. TUTTLE* 

From the beginning of the motion picture the possibilities of its 
application to the field of medicine as an educational medium and a 
means of satisfactory record has been well recognized by the motion 
picture profession. Because of this current feeling there has been 
a constant effort to produce satisfactory pictures. Medical motion 
pictures invariably deal with a specific type of subject in which the 
emphasis lies in detailed structures, which as a rule depend on dif- 
ferentiation of fine color gradations for their successful interpretation. 
Unfortunately these predominant hues are found in the red end of 
the spectrum, that portion which the earlier photographic materials 
were unable to record correctly. This situation, together with the 
fact that photography on 35 mm. film is expensive considering the 
small distribution and limited use to which medical films are subject, 
tended to discourage the progress of these pictures. 

With the introduction of panchromatic film, the problem of color 
rendition in monochrome was solved. The advent of the 16 mm. 
camera and film in 1923 and later the production of panchromatic 
reversal film in 16 mm. size gave a combination which is relatively 
inexpensive and capable of producing pictures of very satisfactory 
quality. 

As a result of the comprehensive program of medical motion pic- 
tures begun in 1927 under the joint auspices of the American College 
of Surgeons, the Motion Picture Producers & Distributors of America, 
Inc., and the Eastman Kodak Company, an organized study 1 was 
undertaken of the technic for making medical and surgical pictures. 
This technic is applicable to the use of 16 mm. pictures as well as 
35 mm. pictures on the same basis of illumination. In either case the 
production of good pictures is the combined effect of proper staging, 

* Eastman Kodak Company, Rochester, New York. (Read before the Society 
at Washington.) 

193 



194 HARRIS B.^urrXE [J. & M. I>. E. 

correct placing of the camera, and the use of properly directed light 
of sufficient intensity. 

During the past decade interest has been increasing in processes 
of color motion pictures, but until very recently none of the processes 
has been used for medical photography. Within the past year 
Naumann 2 has described a rather elaborate equipment for medical 
color motion pictures by the Busch two-color additive process. Al- 
though very pleasing flesh tones can be recorded by a two-color 
process, a much superior color rendering of medical subjects is pos- 
sible by three-color methods. 

There are several processes of color photography which yield a 
transparency as the final color picture. Several of these processes 
have been utilized by surgeons and clinics for recording interesting 
pathological cases. The Kodachrome process, 3 a two-color subtrac- 
tive method devised by J. G. Capstaff, is adaptable to medical photog- 
raphy. Many excellent pictures have been made with this process 
by Dr. Nathan T. Beers of Brooklyn, N. Y. 

The Kodacolor process 4 of amateur cinematography on 16 mm. 
film, announced in 1928, offers a simple, economical, and accurate 
medium for medical color cinematography. It is the purpose of this 
paper to describe several experiments by this process which have been 
conducted during the past few months. Some of these experiments 
were performed with the assistance of Dr. H. H. Baker of the Highland 
Hospital and of Dr. R. Plato Schwartz of the Strong Memorial Hos- 
pital, both of Rochester, N. Y. Dr. Baker recently published a short 
description of his work. 5 

The daylight available for photographic purposes indoors is usually 
of insufficient intensity for medical motion pictures. In any event, 
it is exceedingly variable, changing with the season of the year, the 
time of the day, and the prevailing weather conditions. 

Experiments have shown 1 that incandescent lights are admirably 
adapted to medical cinematography. Carbon arcs obviously cannot 
be used in the operating room because of the danger of ignition of 
the vapors from liquids used for anaesthesia. 

It is possible with incandescent lights to duplicate an exposure, 
and by means of portable units to direct the light almost exactly 
onto any part of the operative field. 

There are, however, certain types of operations which cannot be 
properly lighted with any of the present types of lamp. These are 
mostly of the deep incision type where even the surgeon has difficulty 



Aug., 1930] MEDICAL MOTION PICTURES IN COLOR 



195 



in seeing. The success of medical motion pictures in color lies in 
recognition of the impractability of photographing such cases and 
avoidance of them in the beginning. 

The incandescent tungsten light has a continuous color spectrum, 
suitable for color photography when the filament is burned at the 
rated voltage. Tungsten lights are portable and compact and occupy 
very little space in the usually crowded operating room. They are 
entirely safe to use where ethylene or other inflammable gases are 
used as anaesthetics. 

The quality of light coming from any tungsten filament lamp is 
dependent upon the amount of electric current passing through the 
filament. With the filaments burning at their rated voltage, the 
spectrum of such lamps is not the same as sunlight. If a lamp is 



o 






FIG. 1. Kodacolor filter and diaphragm. 



over-volted, it will burn at a much higher temperature, and the radia- 
tion will contain a greater amount of blue and violet. 

The ratio diaphragm (see A in Fig. 1) which is supplied with each 
roll of Kodacolor film is matched to the film for the sunlight spectrum. 
If this diaphragm were to be placed on the filter in the usual way (see 
Cj Fig. 1) and used with tungsten light at its rated voltage, the re- 
sulting color picture would be too reddish throughout most of its 
tones. If the ratio diaphragm usually supplied is turned around so 
that the section meant to cut down the blue area of the filter is placed 
on the opposite side so that it cuts down on the red area of the filter 
(see D, Fig. 1), that is, if the ratio diaphragm is rotated 180, we have 
found that the color balance is established between Kodacolor film and 
tungsten light so that the resulting pictures will show good color 
rendering. 



196 



HARRIS B. TUTIXE 



[J. S. M. P. E. 



Two types of tungsten filament lamps are recommended for medical 
photography in color: the Eastman Medical Spot Light and the 
Kodalite. 

The Medical Spot Light 1 (see Fig. 2) was designed by the Eastman 
Kodak Research Laboratories for the specific purpose of surgical 






FIG. 2. Eastman Medical Spot 
Light. 



FIG. 3. Kodalite with diffuser. 



motion picture work. A 500 watt tungsten lamp is the illumination 
source. The spot light is so constructed that ;the beam of light 
passes through a water cell (see A , Fig. 2) which absorbs most of the 
heat radiation without diminishing the intensity of the actinic radia- 
tion useful in photography. Therefore, from a practical standpoint, 
this light can be called a cold light, and in consequence it is particu- 
larly adapted to the photography of operations. 

The Kodalite (see Fig. 3) uses a 500 watt tungsten filament lamp 
but is designed for flood lighting. It is important with this lamp that 



Aug., 1930] MEDICAL MOTION PICTURES IN COLOR 



197 



a diffusing medium be used, such as cheesecloth or draftsman's 
tracing linen (see A, Fig. 3). The heat radiation from an undiffused 
Kodalite or any other similar type lamp might cause burn if the pa- 
tient were subjected to it for a long time. 




FIG. 4. Model B Cine Kodak fitted for Kodacolor. 

To make black and white pictures of an operation, it is necessary 
to have approximately 400 foot-candles of light to get good exposure 
at a diaphragm of //4. This, of course, depends somewhat upon the 
color of the subject and the depth of the cavity. If this amount of 
light were used from one source, the lighting would obviously be 
somewhat contrasty. To obtain a softer lighting effect with more 
roundness and less of the deep shadows, it is necessary to use at 
least two lights. The brighter areas of light from the lamps should 
be so directed that they join one another, with the less intense areas 
over-lapping. With two Kodalites diffused with two thicknesses of 



198 HARRIS B. TunxE [J. S. M. p. E. 

cheesecloth, each four feet from the subject and the light directed 
as recommended, the correct exposure at a speed of sixteen frames a 
second would be obtained with an aperture of //4. 

To make Kodacolor at normal speed (sixteen frames a second) 
requires 3200 foot-candles which makes it necessary to use eight Koda- 
lites diffused with two thicknesses of cheesecloth at a distance of 
four feet. It can easily be seen from this that the amount of heat 
from so many lamps and the space they would occupy in the operating 
room would make color cinematography somewhat difficult. The 
number of lamps, as well as the amount of heat, can be reduced one- 
half by using the half -normal speed attachment on the Cine Kodak 
(see Fig. 4). By moving the lights up to three and a half feet, one 
more can be eliminated, reducing the number to three. So, with three 
Kodalites, approximately three and a half feet from the subject, and 
the camera operating at half normal speed, satisfactory Kodacolor 
pictures can be made. 

The Medical Spot Light because of its design gives a concentrated, 
uniform spot of light. Therefore, in case of its use, only two lamps 
are necessary at a distance of four feet from the field for taking Koda- 
color pictures at half normal speed. 

The foregoing illumination conditions assume that the average 
operating area will constitute the photographic field. If the field is 
greater than the operating area, then an additional 500 watt flood 
light should be used with the Medical Spot Light for general illumina- 
tion. 

Regardless of the type of lamps used, they should be placed so that 
there are no deep, heavy shadows. Flat, even lighting is better in 
color work than contrasty lighting. 

It has been found in most cases that the most convenient place 
for lights and camera is at the foot of the operating table. The table 
can sometimes be slightly tilted toward the camera to improve the 
perspective. 

At present, lenses of 1.0 in. equivalent focal length are the only 
ones available for making Kodacolor motion pictures. To meet this 
condition, it is necessary to place the camera about three feet from 
the subject. 

Precautions to assure asepsis of the cinematographer and his equip - 
men in operation pictures are extremely important because of the 
proximity of the apparatus to the field. 

It is the practice of a great many hospitals to use either iodine or 



Aug., 1930] MEDICAL MOTION PICTURES IN COLOR 199 

mercurochrome in sterilizing the area of operation. Both of these 
absorb a considerable amount of the heat radiation from the lamps. 
It is therefore recommended that alcohol and Kalmerid solution be 
used for sterilization. Both of these solutions are practically color- 
less and are being used entirely by a large number of hospitals at the 
present time. 

In the following two tables, the approximate illumination intensities 
in foot-candles are given for the Eastman Medical Spot Light and the 
Eastman Kodalite. 

TABLE I 
Illuminating Intensities for Eastman Medical Spot Light 



Distance from 
Front of Lamp 
to Subject 


Diameter of 
Spot of Light 


Approximate 
Intensity 
(Foot-Candles) 


3 feet 


6 inches 


1800 


4 feet 


9 inches 


800 


5 feet 


12 inches 


450 


6 feet 


15 inches 


300 


7 feet 


18 inches 


200 


8 feet 


21 inches 


150 



TABLE II 
Illuminating Intensity for Eastman Kodalite 



Diffusing Material 

Distance from Two Thicknesses One Thickness 

Front of Lamp of Cheesecloth Tracing Cloth 

to Subject Approximate Intensity (Foot-Candles) 

3 feet 700 350 

4 feet 400 200 

5 feet 250 125 

6 feet 180 90 

7 feet 120 60 

8 feet 100 50 



The efficiency of a light unit may decrease with use, because of 
a blackish deposit which collects on the inside of the glass bulb. 
Lamps are available, however, that contain tungsten powder, with 
which the blackening can be removed thus prolonging the useful life 
of the lamp. For color motion picture photography, this type of 
lamp should prove useful. Allowance for decreased light with a 



200 HARRIS B. TUTTXE 

blackened bulb must be made in the exposure when the old type of 
lamp is used. 

SUMMARY 

Members of the medical profession interested in making clinical 
and surgical motion pictures have felt strongly that the addition of 
color would increase the usefulness of such films. Satisfactory 
medical motion pictures in color on 16 mm. film have been made with 
the use of a camera equipped to operate at eight frames per second. 
Three Kodalites placed three and a half feet from the subject or two 
Eastman Medical Spot Lights placed four feet from the subject give 
ample illumination. To prevent over-exposure in the red the ratio 
diaphragm supplied with each roll of Kodacolor film should be fitted 
on the filter holder in reverse from the manner recommended for 
daylight pictures, where blue and violet radiations predominate. 

REFERENCES 

1 TUTTLE, C., AND MORRISON, C. A.: "Some Preliminary Experiments in 
Medical Photography," Trans. Soc. Mot. Pict. Eng., XII, No. 36 (1928), p. 1022. 

2 NAUMANN, H.: "The Busch Two-Color Film in the Service of Medicine," 
Phot. Korr., 65 (April, 1929), p. 117. 

3 "An Important Development in Color Photography," Sci. Amer., 112, 
(April 10, 1915), p. 341. 

4 CAPSTAFF, J. G., AND SEYMOUR, M. W. : "The Kodacolor Process for Amateur 
Color Cinematography," Trans. Soc. Mot. Pict. Eng., XII, No. 36 (1928), p. 940. 

5 BAKER, DR. H. H.: "Color Photography in Surgery," The Camera, 40 
(March, 1930), p. 184. 

6 WRIGHT, D. K., AND EGELER, C. E. : "Bulb Cleaner for Incandescent Lamps," 
Trans. Soc. Mot. Pict. Eng., XIH, No. 38 (1929), p. 346. 

DISCUSSION 

MR. ROSENBERGER: I appreciated these pictures very much, but the only 
objection I would have is that for medical studies these motions are about twice 
too fast. I think it would be better to increase the light if possible and take the 
pictures at normal speed instead of eight per second. 



APPARATUS FOR THE ANALYSIS OF PHOTOGRAPHIC 
SOUND RECORDS* 

OTTO SANDVIK 

The origin of the distortions which occur in the photographic sound 
recording process may be classified in four general groups, namely, 
electrical, optical, mechanical, and photographic. 

The group of instruments to be described here were designed for 
the purpose of studying the various phases of the photographic proc- 
ess alone. Broadly speaking the only condition to be satisfied by 
the photographic process is that the positive transmission be propor- 
tional to the negative exposure. 

The literature dealing with the photographic problems connected 
with the variable width sound recording process is limited, and that 
devoted to the problems relating to the variable density method is 
more extensive but represents primarily deductions from the general 
theory of tone reproduction. The theory is valuable as a working 
basis for certain phases of the problem which, however, has many 
other aspects, and a great many data are required before a practical 
application of this theory alone can be made. Such data should deal 
with the characteristics of photographic materials under conditions 
which obtain in the practice of sound recording and sound reprodul- 
tion. For example, owing to the failure of reciprocity, the sensitivity 
or the speed of an emulsion determined by means of a step tablet or 
any type of sensitometer where the exposure time is relatively long, 
may yield results differing considerably from those that will be ob- 
tained when the intensity factor of exposure is very great and the 
exposure time is of the order of 5 X 10 ~' second which is true in prac- 
tice. Moreover, densities measured on a reliable densitometer of the 
type with a diffusing medium against the film sample, give values 
which are quite different from the values that would be obtained with 
a photo-electric cell as used in a standard sound reproducer. In the 
former cases the values obtained are so-called diffuse densities, while 

* Communication No. 438 from the Kodak Research Laboratories. (Read 
before the Society at Washington.) 

201 



202 OTTO SANDVIK [j. s. M. p. E. 

in the latter the values are more nearly specular densities. The dif- 
ference between these two values depends upon the type of photo- 
graphic material used, the type of optical system, and on the abso- 
lute value of density. 

At this point it may be well to mention that where it is required to 
develop a routine method of sensitometric control in a processing 
laboratory, it will ordinarily be found quite satisfactory to use a 
low intensity sensitometer, and a densitometer that reads diffuse 
densities, so long as the control is restricted to the material and the 
conditions for which it has been determined. Discordant results 
would generally be obtained, however, if one were to measure rela- 
tive speeds of two different types of emulsions at low values of il- 
lumination, and apply the speed ratios, so found, at very high exposure 
intensities, the reason being that the deviation from the reciprocity 
relation may, and very probably would be different for the two ma- 
terials. Likewise, the gamma product relation of negative and posi- 
tive based on values of either specular or diffuse densities, may lead 
to discordant results were one of the emulsions changed. To il- 
lustrate: A series of experiments on two photographic materials has 
shown that the best results are obtained when the gamma product has 
a certain value, a, as based on diffuse densities. The positive is not 
changed materially and it is found that the best quality is obtained 
with a gamma product larger than a, or it may be less than a. Since 
the densities of the positive were measured as diffused densities, 
whereas the photo-cell in the reproducer measures more nearly 
specular densities, this apparent discrepancy may be accounted for 
by a difference in the ratio of the values of density obtained by the 
two methods of measurement in the two cases. These factors will 
be treated in greater detail in a subsequent paper which will present 
experimental data dealing with the various phases of the problem. 

From the above brief statement of the problem it appears that the 
sensitometric study should be carried out according to precisely 
defined conditions, and that it is desirable to duplicate exactly condi- 
tions which obtain in practice. Moreover, having formulated a 
satisfactory method of sensitometry, it remains to subject the results 
obtained to critical quantitative analysis. This can be accomplished 
by analysis of the wave-form of the sound records. 

Before proceeding with a description of the instruments for the 
analysis of wave-form it may be well to consider briefly the problem 
itself. As already stated the condition to be satisfied by the photo- 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



203 



graphic process is that the positive transmission shall be proportional 
to the negative exposure. In order, however, to study the relation 
between negative exposure and positive transmission it is necessary 
to know the exact distribution of exposure along the film, where the 
distribution of exposure is defined so as to hold for either variable 
density or variable width type of recording. For the purpose of 
simplicity let it be assumed that the exposure modulating device is 
actuated by the current from a source which delivers a pure sine 
wave. The distribution of exposure on the film, however, will not 
be sinusoidal on account of certain distortions occurring during the 
transformation of a variable electric current to a variable exposure 




FIG. 1. Photograph showing front view of microdensitometer. 

(width, intensity, or time). The cause of these distortions may be 
optical, due to finite slit width, imperfect image formation, diffrac- 
tion, or similar cause, electrical, or purely dynamic. The form and 
amplitude of these can be ascertained with a fair degree of accuracy 
by measurements and by calculations which are based on fundamental 
principles. 

In general, non-linearity between the variation in the sinusoidal 
current which actuates the modulating device and the correspond- 
ing variations in the intensity of the radiation transmitted through 
the positive sound track moved uniformly past a scanning slit, may be 
due to three causes: first, distortions introduced during the "electro- 
optical" transformation, that is, by the modulating device; second, 
distortions introduced by the photographic process; third, distortions 



204 



OTTO SANDVIK 



[J. S. M. p. E. 



in the "opticoelectrical" transformation due primarily to a finite 
slit width and non-uniformity of the image formed by the optical 
system of the reproducer. In the investigation which is to follow, 
these three factors will, so far as possible, be studied separately so 
as to determine step by step what is occurring. 

There are three instruments to be described. The first is a micro- 
densitometer shown in Figs. 1 and 2. This instrument traces out 
the wave form of the sound record on a scale eighty times as large in 
amplitude with a proportionally magnified base line. It consists of 
a microscope with a moveable microscope stage driven by a precision 




FIG. 2. Photograph showing a side view of microdensitometer. 



screw, and a carefully made train of gears from a synchronous motor. 
(The motor need not necessarily be of synchronous type.) The mi- 
croscope stage is so constructed that it can be shifted laterally for 
the purpose of analyzing different sections across the sound track or 
the entire sound track, as is, of course, necessary in the case of variable 
width records. It can also be rotated about the optic axis in its own 
plane, so as to place the longitudinal axis of the sound track parallel 
to the axis of the screw. The train of gears provides speed reduction 
ratios such that the screw will advance the microscope stage at the 
rate of 5, 2.5, 1, 0.5, or 0.25 mm. per minute, respectively. The speed 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



205 



at which the stage should be advanced depends on the time constant 
of the recording system and on the structure of the image to be ana- 
lyzed. A reversing gear is provided, and records may be traced with 
the screw running in either direction. The film with the sound record 
runs over a guide, or gate, which is elevated slightly above the plane 
of the microscope stage ; this provides accurate side guiding and pre- 
vents the film from buckling and moving out of the focal plane. 

The optical system (Fig. 3) consists of a tungsten ribbon lamp, O, 
imaged on the film by a pair of condensers, C\ and C*. When the sub- 
stage condenser, C%, is removed, the ribbon can be imaged on the film 
full size or larger so as to more than cover the entire width of the 
sound track. By careful choice of ribbon, very uniform illumination 




Schematic diagram of the optical system of the 
microdensitometer. 



across the entire track can be obtained, which, of course, is essential 
for the analysis of variable width sound records. A copper sulfate 
cell, W, is inserted between the two condensers as shown, its purpose 
being to filter out the infra-red radiation (to prevent excessive heating 
of the film) where this part of the radiation does not contribute ma- 
terially to the response of the photo-sensitive surface. This is the 
case for most types of photo-electric cells. An image of the sound re- 
cord is formed by a microscope objective, LI, on an adjustable slit 
placed in front of the photo-sensitive surface. The focal length of 
the objective and the slit width depend on the magnification and 
resolution desired. A cylindrical lens, L^, may be inserted in the 
beam at the point shown to reduce the magnification along the longi- 



206 



OTTO SANDVIK 



[J. S. M. p. E. 



tudinal axis of the slit. It has been learned by experience that a 
certain amount of reduction is possible without materially affecting 
the definition in the image plane. 

It is desirable in the present investigation to use a photo-electric 
cell for the photo-sensitive element. It is well known that photo- 
electric cells are not uniformly sensitive over the surface, but that 
the sensitivity varies from point to point. When the image of a 
variable area sound record is caused to move across the slit in front 
of the photo-cell by the motion of the microscope stage carrying the 
record, the area and the location on the cell which is illuminated 




FIG. 4. 



Schematic diagram of the camera optical system of 
the microdensitometer. 



do not remain constant, but will shift up or down as the phase of 
the wave advances. Therefore, if the sensitivity of the cell changes 
from point to point, the variation in photo-electric current will not 
be proportional to the variation in the total radiation falling on it. 
To overcome this difficulty a lens is placed behind the slit in a position 
such that it images the gauss point of the microscope objective on the 
cell surface. This forms on the cell an image of which the size is 
constant and of which the intensity is essentially uniform. The in- 
tensity of this image depends on the amount of radiation transmitted 
by the slit. 

The camera (at the right in Figs. 1 and 2) is driven through an- 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



207 



other system of carefully made gears from the same shaft which drives 
the microscope stage. Therefore, the film and the microscope stage 
are driven at a constant ratio of speeds for any given gear combina- 
tion. The gear reductions on the camera are such as to advance the 
film at rates of 1000, 500, 200, 100, and 50 mm. per minute. This 
wide range of speed is not necessary for the purpose of analyzing 
sound records, but the instrument was designed so as to be useful 
also for other purposes. The film on which the trace is made is about 
165 mm. (6.5 inches) wide and can be inserted in the camera in 400 




FIG. 5. Photograph showing side view of sound track densitometer. 



foot lengths. Any length may be detached as required for develop- 
ment. 

A top view of the camera optical system is shown in Fig. 4. A 
vertical slit, S, is illuminated by a lamp, 0. The radiation from the 
slit passes through a lens, LI, to the galvanometer mirror, M, from 
whence it is reflected on the film, F. The lens images the slit on the 
film through a cylindrical lens, L 2 , which brings the slit image down to 
a point image on the film. Stops may be introduced in the lens for 
the purpose of obtaining the correct exposure at different film speeds. 



208 



OTTO SANDVIK 



[J. S. M. P. E. 



The galvanometer is shown placed on a suspension for the purpose 
of eliminating vibrations. 

The wave form of the microdensographs will be analyzed and re- 
solved into the component parts by means of a harmonic analyzer of 
the Henrici type built by the Mathematical-Mechanical Institute of 
G. Coradi, Zurich, Switzerland. This instrument is designed to give 
ten terms of the Fourier series, and by a slight modification it will 
give thirty terms if so desired. 

The second instrument which may be called a sound track densi- 
tometer is shown in Fig. 5. This instrument is so designed as to ap- 




FIG. 6. Schematic diagram of one optical system and 
film moving mechanism of sound track densitomer. 

proximate closely the conditions of a standard sound reproducer, ex- 
cept that the film, instead of being moved at a speed of 90 feet per 
minute by a rotating sprocket, is moved step by step past the scanning 
slit by the rotation of a very accurate screw mechanism. 

The purposes of this instrument are fourfold: first, to measure photo- 
electric densities in connection with sound recording emulsion sensi- 
tometry; second, for practical wave form analysis; third, for prac- 
tical or experimental investigations of the effect of slit widths, orien- 
tation of the slit, and lack of focus ; and fourth, to make a study of the 
relative merits of various types of optical systems. 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



209 



The film is held taut between two planes which may be moved up 
or down by means of the screw as shown in Fig. 6. This screw is 
guaranteed by the maker to have an error less than 0.001 mm. With 
the divided head on the screw one can set it accurately to 0.005 mm. 
and with close approximation one-half of that. In other words, the 
sound track can be advanced in steps of 0.0025 mm. The transmis- 




FIG. 7. Schematic diagram of another optical system of sound 
track densitometer. 

sion, step by step, is determined by readings of photo-electric cell cur- 
rents. Since the wave-length on the film moving with a linear speed 
of about 457 mm. per second (90 feet per minute) is about 0.91 mm. for 
a 5000 cycle frequency, one can obtain 36 readings from to 2ir 
with a proportionally greater number for lower frequencies. This 
gives a sufficient number of points on which to plot a good curve of 



210 



OTTO SANDVIK 



[J. S. M. p. E. 



the wave, which can if desired be analyzed on the harmonic analyzer. 
The film slides between two stationary planes in which there are small 
rectangular apertures providing passage for the radiation through the 
film to the photo-cell. The purpose of the stationary planes is to 
firmly fix the film in the image plane of the slit. 

The lamp filament, O, is imaged on the slit by LI as shown in Fig. 6, 
and the slit is imaged on the film by L 2 . The photo-cell is mounted 
on a slide so that its front surface may be placed within about 15 
mm. of the film plane or as far as 100 mm. away from that point. 




FIG. 8. Photograph showing side view of variable slit sensitometer. 

A different type of arrangement is shown in Fig. 7. The radiation 
from the lamp, 0, is condensed on the film by a lens, LI. Another 
lens, L 2 , is placed on the opposite side of the film so as to project an 
enlarged image of the sound track on the slit, S, in front of the photo- 
electric cell. This scheme is not new, in fact, it is nothing more than 
a projection microscope, but it will be interesting to compare the rela- 
tive merits of the two systems. One obvious advantage of it is that 
focusing and alignment of the slit is less difficult, because one can 
actually see the grains in the film when they are brought to a focus 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



211 



on the slit jaws, and the slit can then be rotated until it is perpendicular 
to the sound track. Experimental data obtained with the two sys- 
tems will be presented in a subsequent paper. 

The third instrument is a variable slit sensitometer, designed for 
the purpose of investigating the sensitometric characteristics of sound 
recording emulsions, as for example, sensitivity or speed and failure 
of reciprocity under sound recording conditions. The instrument is 
shown in Fig. 8. It consists of a camera moving the film at a uniform 
speed of 90 feet per minute past an exposing slit of variable width. 
The light source is a tungsten ribbon filament lamp. The lamp fila- 




FIG. 9. Schematic diagram of optical system and film path in 
variable slit sensitometer. 



ment is imaged on the variable width slit which in turn is imaged on 
the moving film at two to one reduction, as shown in Fig. 9. 

The width of the slit is varied automatically by the rotation of a 
precision screw. This screw is guaranteed by the maker to have an 
error of less than 0.001 mm., and since it turns through only a very 
small angle, the error is probably more nearly of the order of 0.0001 
mm. The screw is actuated by a cam mechanism. This mechanism 
can be understood more easily by referring to Fig. 10. One member 
of the cam mechanism consists of a cylindrical drum around the pe- 
riphery of which are placed a series of stops. An arm pinned to 



212 



OTTO SANDVIK 



[J. S. M. p. 



the screw shank extends out from the screw so as to rest on one of 
these stops while the exposure is made. Another member of the cam 
mechanism, in fact another cam, rotates continuously and when it ad- 
vances in a given angular position it engages the arm which controls 
the rotation of the screw and lifts it to a point which clears the 
highest stop on the cylindrical cam. The latter is now advanced one 
step by a ratchet mechanism and stops ; the arm which rotates the 
screw is now brought back into this new position and the slit opening 
is varied by a correspondingly different amount, where it remains 
while a second exposure is being made. This process continues 
through the complete cycle of the cylindrical cam when the process is 
repeated. 




FIG. 10. 



Drawing showing top view of slit and cam jnedianism of 
variable slit sensitometer. 



Figure 1 1 gives a better idea of the slit and cam arrangement with 
respect to the film which is shown wrapped around the drum. There 
are sixteen stops on the cylindrical cam so arranged that the width of 
the variable slit is changed by square root of two steps from a slit 
width of 4 mils to about 0.016 mil. This range of variations is more 
than sufficient to cover the normal exposure range occurring in prac- 
tice. 

DISCUSSION 

MR. COFFMAN : I feel that the Papers Committee owes Dr. Sandvik an apology 
in forcing him to abridge his talk so materially. I strongly urge every one in- 
terested in recording sound on film to study the description of the instruments 
when the paper is published in the JOURNAL,, because these instruments make it 
possible to secure real precision data on what happens in photographic sound 



Aug., 1930] 



PHOTOGRAPHIC SOUND RECORDS 



213 



recording. The instruments are ingeniously designed and the results should 
throw light upon a number of our most mooted questions. 

MR. TAYLOR: I hope in addition to the illustrations of the machines we shall 
have the results of what is obtained with them. 

MR. COFFMAN: I should like to reply to Mr. Taylor for Dr. Sandvik. Dr. 




FIG. 11. 



Photograph showing slit and cam mechanism of variable slit 
sensitometer. 



Sandvik insisted that the description of these instruments should not be presented 
to the Society until the data secured with them was ready for publication; but 
I thought they were sufficiently interesting to excite thought on how they could 
be used. The Papers Committee will insist on publication by Dr. Sandvik of 
his results as soon as they are ready for release. 



PROGRESS IN INDUSTRIAL AND SCIENTIFIC 
CINEMATOGRAPHY IN FRANCE* 



MARCEL ABRIBAT 

The notes and information which follow treat very briefly the ac- 
tivities in the sound film industry in France for the late months of 
1929 and the early part of 1930. This information is followed by 
descriptions concerning some innovations in motion picture ap- 
paratus, both planned and effected in France during these months. 
Only the most interesting of these will be described. 

THE SOUND FILM SITUATION IN FRANCE 

The introduction of sound film in France has been very slow. The 
causes of this slow beginning are many, but among them only the 
most important will be cited: (1) The lack of enthusiasm of the pub- 
lic and the producers for synchronized talking films. These, al- 
though very poor technically, had appeared even before the war and 
had cooled the spark of curiosity which would have been shown for 
the new sound films coming from across the Atlantic. (2) The dis- 
agreement between the American and French producers who during 
the year of 1929, had not been able to come to a suitable agreement. 
If sound films had become immediately popular in France, it could 
only have been by the use of American material and films, and the 
time for this was evidently poorly chosen. 

Toward the end of the past year and in the beginning of 1930, the 
situation cleared up somewhat. An agreement concerning the free- 
dom of entry of foreign films having been established for better or 
worse, it has now become possible for certain foreign firms to enter 
freely under an agreement with the French producers and French 
theaters. 

More and more, the old French firms are changing and increasing 
their activities and those having means for both production and exhi- 
bition have already entered actively into the field. 

Among these, Pathe Cinema, really Pathe-Natan, having at its 

* A contribution to the Progress Committee Report of May, 1930, by 
M. Abribat, Kodak-Pa the Research Laboratory, Vincennes, France. 
214 



PROGRESS IN CINEMATOGRAPHY 215 

disposal both important exhibition circuits and enormous studios at 
Joinville (formerly studios of the Socie'te' des Cineromans) has com- 
menced sound productions on a large scale. 

The process used is the RCA and one after the other of the studios 
at Joinville have been equipped for sound taking work, or to use the 
technical word already current, they are "Sonorisfc." 

During the delay in changing the French studios, Pathe-Natan 
filmed in the studios of the British International at Els tree, England, 
Les Trois Masques, a film spoken in French, which has run for many 
weeks now on the Parisian "boulevards." 

No special technic was employed in the large French speaking 
production (featuring Adolph Menjou) in the Pathe-Natan studios 
of Joinville but the RCA process was exactly as in the United States. 

La Socite* des fitablissements Gaumont even before the war pro- 
duced short synchronized films with disks and for several years and 
even in these past few months used the Danish Petersen-Poulsen 
process. The sound is recorded on the entire width of a separate 35 
mm. film. Recording is by variable width method. The reproduc- 
tion necessitated the use of two films (one film for sound and one for 
picture) passed, respectively, through the reproducer gate and a 
separate projector in synchronism. 

Gaumont, who already has equipped the Buttes Chaumont studios 
in Paris for sound work and has produced some experimental film, has 
a new projection apparatus called 'T Ideal Sonore." This reproduc- 
ing arrangement uses a selenium cell as in the Gaumont-Petersen- 
Poulsen system. The apparatus is fitted with a turntable for phono- 
graph records. 

A public demonstration given recently at the theater of the 
Champs filysees in Paris showed that the Gaumont 1' Ideal Sonore 
is able to give an excellent rendition from any films, Gaumont, 
RCA, Movietone, Tobis, as well as disk processes: Vitaphone, 
L. N. A., etc. 

Aloel Gance productions used the new Gaumont sound process for 
their film La Fin du Monde. 

On the other hand, the Societe* Gaumont has recently joined the 
powerful Aubert-Franco-Film group and large productions are being 
planned. The same group has already taken under its direction the 
G. M. Films developing and printing studios and the firm of motion 
picture equipment makers, Continsouza. It is therefore likely that 
the new group will be able to extend its activity into all the branches 



216 MARCEL ABRIBAT [j. s. M. P. E. 

of the motion picture industry, production, distribution, and ex- 
hibition. 

The firm of Tobis, which was one of the first to introduce a non- 
American sound apparatus in France, has completed the equipment 
of their Menchen d'Epinay studios where they are actually producing 
films. The Tobis and Klangfilm processes are used, employing either 
a Kerr cell or lamp. 

As in all the French sound studios, lighting for the scenes is done 
by incandescent lamps: Nitraphot, Pyralux, and Phillips, from 600 
to 5000 watts. The Tobis studios employ arcs with filters successfully. 

In its latest installation, Tobis has given up the system employing 
a camera booth for sound recording. A fixed central station in the 
center of the studio and in communication with the different rooms, 
receives the current by wire from the microphones placed on the 
different sets. The recording apparatus is simply encased in a rubber 
box. The operator and his camera can thus move as freely as they 
could when taking silent films. 

The equipment for these studios is imported exclusively from Ger- 
many. Moreover, the Tobis company leases its studios and its ma- 
terials to different companies. 

A film which has had a great success is La Nuit Rst a Nous filmed 
in Berlin in three languages simultaneously with artists of three 
different nationalities. The French version is very satisfactory. 

La Societe Haik exploited its "Cinevox" process which is a varia- 
tion of the DeForest process where recording is accomplished with a 
glow lamp. Original work dealing with amplifiers and loud speakers 
has been carried out by the engineers of this society. Unfortunately 
the studio at Courbevoie which was operating successfully was almost 
completely destroyed by fire on Feb. 8, 1930. Productions under way 
are being continued in the studios on location, but a good part of the 
material was destroyed. 

La Societe L. N. A. headed by Louis Nalpas, formerly director of 
the Societe des Cineromans, built a projector for disk and film records. 
This projector is simple and inexpensive. This, together with Gau- 
mont's Ideal Sonore, should help in spreading sound films in parts 
of France where the talkies have scarcely penetrated or have not been 
introduced at all. 

The L. N. A. company is producing in the Billancourt studios where 
they are now working on synchronization of silent film and the making 
of song films. 



Aug., 1930] 



PROGRESS IN CINEMATOGRAPHY 



217 



La Socie'te' Melovox formerly allied with Gerardot built a machine 
for film and disk sound records. There is nothing particularly novel 
about it technically. The Melovox company does not make film 
itself. 

Les Productions Robert Kane, an American organization, started 




FIG. 1. Debrie sound proof camera case. 



first with the RCA process. This firm erected a studio on the grounds 
of the former Joinville studios. 

From this very brief exposition, it is seen that the purely French 
processes for sound films are not numerous. The process for record- 
ing on film used by the Gaumont company is the only one which is 
actually complete from the taking to the showing with the Ideal 
Sonore projector mentioned above. 



218 



MARCEL ABRIBAT 
NEW APPARATUS 



[J. S. M. P. E, 



New Anti-sound Case for Camera and Printing Device. A sound 
proof case for acoustically insulating the taking apparatus has been 
built by A. Debrie. The camera is mounted on a platform and a 
cover is lowered over it, sealing it hermetically. (See Fig. 1.) The 
case is arranged so as to allow for the necessary freedom of movement 
for loading and for changing the lenses. All the controls for film 
punching, automatic dissolve, etc., may be reached from the outside 
of the case. The focusing magnifier is placed very ingeniously. The 




FIG. 2. Speico projector showing tractor rollers. 



eye-piece remains fixed on the box and it is therefore possible to open 
and close the box without it being necessary to readjust the magnifier. 
The closed box assures perfect insulation from the sound produced by 
the camera mechanism. 

For printing sound films the studios were obliged to use continuous 
printers. The firm of A. Debrie has adapted to its well known printer 
"Matipo" an arrangement for printing by an illuminated slit. The 
device is placed on the printer and the negative sound film runs con- 
tinuously in contact with the positive which has just come from the 
gate where the picture is printed as usual. All the French printing 
studios have adopted this device including French Tobis in their 
Epinay studios. 



Aug., 1930] 



PROGRESS IN CINEMATOGRAPHY 



219 



New A pparatusfor Handling Endless Film the ' 'Speico' ' Box. * The 
problem of unrolling and rolling up simultaneously of a film on the 
same roll is not new and numerous tentative suggestions have already 
been made for solving it. 

The "Speico" device consists of a flat cylindrical case containing 




FIG. 3. Speico projector loaded with film. 



several cylinders whose axes are arranged radially. (See Fig. 2.) 
These cylinders may be turned around on their axes and are carried 
at equal speeds by means of a bevel gear. One of these cylinders is 
connected to each of the extremities of a vertical drum to guide the 
film from its entrance to its exit from the case and to keep a constant 
length of film on the outside of it. The circumferential leading of a 
reel of film placed on the rolls in question is solved by the grooves of 
this reel being in contact with the generators of the rotating cylinder. 
All the grooves are turned at the same speed irrespective of their 
distance from the center. 

The Speico company, which supplies boxes holding up to 3000 

* BOITIER, SPEICO. Recherches et Inventions, 180 (1929), p. 233; Ibid., 183 
(1929), p. 326. M. R. Hue, French Patent No. 532,312, issued Jan. 11, 1928. 



220 



MARCEL ABRIBAT 



[J. S. M. p. E. 



meters of standard film, has perfected a projector which may be very 
easily mounted on the film box. This projector (Fig. 3) has some 
interesting innovations, one of which is a result of the use of the box. 
Abolition of upper and lower sprockets, abolition of framing, and an 
arrangement for simultaneous ventilation of film and lantern and use 
of a device for humidifying are features which are incorporated. 

Marcel R. Hue Projector with Continuous Film Movement. This 
apparatus is based on the known principle shown schematically in 
Fig. 4. The film is inserted in the direction of the arrow, 2, guided 
by a track, 3, which has an opening window, 4, which is the width 
of the image, 5, of the film and about the height of two images. The 





FIG. 4. Schematic drawing illustrating 
the principle of the Hue non-intermittent 
projector. 



FIG. 5. Diagram of cam. 



light rays pass from the light source, 6, through the condenser, 7, 
on to the portion of film in front of the Window, 4. The track, 3, 
in the form of a part of a cylinder whose axis, 8, passes through the 
reflecting face of a polished optical surface, 9, capable of turning 
around this axis. If the film is passed in front of the window with an 
angular speed, co, and at the instant the mirror turns in the direction 
of the arrow, 10, with an angular speed, a/ 2, the virtual image, 11, 
will be immobile on the lens, 12, which will give a real image on the 
screen, 13. On the contrary, the virtual image of the edge of the 
window, 4, appears to move in front of the fixed virtual image, 11, 
with a speed, co, in the direction of the arrow, 2. M. Hue's patent 
claimed from the first the use of ordinary interchangeable lenses of 
different focal lengths. On the other hand, the window, 4, having a 



Aug., 1930] PROGRESS IN CINEMATOGRAPHY 221 

greater height than that of a single frame, the screen will receive the 
image of one picture accompanied, above and below, with portions 
of two adjacent frames. The patents claim a remedy for this ob- 
jection consisting in the use of a movable window, 14, integral with 
the mirror, framing exactly the frame in the projector and accompany- 
ing it exactly in its movement. The movable window is cut in one 
piece sufficiently large to mask the adjacent frames. 

A machine made exactly according to the diagram in Fig. 4 will 
give images which are visible in their normal position only to a spec- 
tator placed behind the supposedly translucent screen, 13. It is 
therefore necessary to correct this projection either by inserting a 
plane mirror or a totally reflecting prism in front of the lens and at 
45 degrees to the axis, 11-13, or by turning the projected film around 
and by making it run in the desired direction in its track. The first 
of these methods is objectionable in that it leads to the use of lenses 
of great focal length which, in certain cases, may call for supplemen- 
tary optical systems for enlarging the image on the screen. 

The analysis of the mechanism of the machine is as follows: 

One frame, surrounded by the mobile window, 14, begins to descend 
while the mirror, 9, begins to turn. At this moment, the shutter of 
the lens unmasks it. The mirror, 9, continues to turn until the upper 
edge of the picture has descended the length, A (less than the height 
of one frame) , starting from the upper edge of the window, 4. The 
shutter then closes over the lens while the window, 14, and the mirror 
stops. While the shutter masks the lens, these two pieces return to 
their initial positions. This takes place progressively and without 
impact during the time that the frame has covered the distance, 
B to A , B being the height of one frame. It is evident that this time, 
which corresponds to the shutter period is a little less than the rela- 
tion A/B, and approaches unity. The window and the mirror having 
come back to their initial positions, the movements described above 
are repeated, and so on for each frame of the strip. 

Fig. 5 represents the diagram of a cam meant to engage through the 
intermediary of a lever with the roller, 1 (Fig. 4). The cam corre- 
sponds to the simple case where the pull down sprocket advances 
the film one frame for each revolution. Since this cam is supposed 
to turn in the direction of the arrow, the time the roller takes to cover 
the distance, abode, corresponds to one picture cycle in projection. 
The lens is masked during the time which corresponds to the line, efa. 
The angle, a, determines, therefore, the time of projection and the 



222 



MARCEL ABRIBAT 



angle, 0, that of occultation. The time of occultation will bear a rela- 
tion to the time of projection as jS/a and according to the author a 
sufficient reduction of this ratio permits dispensing with the shutter. 
In the case of engagement of the film by the usual sprockets 
(4 frames per turn) and by using a cam resembling that which has just 
been described, a multiplication of auxiliary gears becomes necessary 
but then the least play between the teeth of the gears interferes with 
the precision of the mirror drive, 9. This objection is eliminated 




FIG. 6. Application of the Hue principle to a practical projector. 



by engaging directly to a cam which has as many depressions as the 
sprocket engages pictures per revolution. 

M. R. Hue's patent provides several arrangements for framing. 

Figure 6 represents schematically a practical realization of the 
principles which have been pointed out. 

In closing I thank my colleague, M. L. Didiee, for the valuable 
collaboration which he has given in the preparation of this report. 



APPLIED AND SCIENTIFIC CINEMATOGRAPHY 
IN AUSTRIA* 

PAUL SCHROTT 

PRODUCTION 

At the present time the production of motion pictures in Austria 
is limited by lack of financial support. In Vienna, the center of the 
Austrian film industry, there were several important studios before 
the war, while now there are but four. Three of these are in current 
use and are very well equipped. They are not used by one company 
alone, but are rented to different ones in turn. The fourth studio, 
which is better equipped than the others, is not in use at present. 
It has been purchased by an English company, has been rebuilt for 
sound work, and production is scheduled for an early start. 

Austrian film production is impoverished. To avoid a crash in 
the industry, a "Film Kontingent" has been formed, which governs 
film importation and production. 

There has been more progress in the scientific applications of 
cinematography. A special course has been formed at the Technical 
High School in Vienna, where classes are held in technical and scien- 
tific cinematography, and the students gain a thorough training in 
theory and practice. This institute is headed by the writer. 

CINEMATOGRAPHY OF ATMOSPHERIC STRIAE AND SIMILAR REFRACTION 

PHENOMENA 

During the past year there has been considerable work done on 
photography by spark illumination, and the photography of atmos- 
pheric striae and similar refraction effects. This work is still in 
progress. The writer in his investigations is using Topler's method. 
The principles are as follows: 

A slit, ab (Fig. 1), is illuminated by a light source, L, and by means 
of the illuminating lens, BL, a sharp image, a 'b', is produced at the 
diaphragm, SB. This diaphragm is so shaped that it just obscures the 

* A contribution to the Progress Committee Report of May, 1930, by Dr. 
Schrott, Technical High School, Vienna, Austria. 



224 PAUL SCHROTT [J. S. M. P. B. 

entire image, a'b' . By this arrangement no specular light from lens, 
BL, enters the imaging lens, SL, which is in contact with the dia- 
phragm, SB. If a transparent body, S, having a refractive power 
which differs from that of air, e.g., heated air, carbonic acid, ether 
vapor, etc.; is placed in the beam of light near the lens, BL, then the 
beam will be deflected. Some of the beam will then pass the edge 
of the diaphragm and enter the lens, SL. The result is that lens, 
BL, and the object, S, are sharply imaged by the lens, SL. This 
image can be viewed by means of an eyepiece, projected on a screen, 
or photographed on a film or plate. 

Topler employed an Argand burner, the flame of which fills the 
entire slit. Now the brightness of the image at SB depends on the 
intensity of the refracted rays, hence on the brightness of the area at 
ab. For this reason the images Topler obtained were not very bright, 
and could be observed only with an eyepiece. 

An arc lamp was used as a light source for cinematography with this 




FIG. 1. Optical system for the photography of striae. 

apparatus. On account of the relatively short time required for 
taking the pictures, it is quite easy to keep the arc constant enough 
after the carbons have burned some time. Goerz-Beck carbons are 
used. These carbons have a heavy copper coating, and give a very 
intense and steady light. A quartz mercury vapor lamp (Hanan) 
will give good results, but low pressure mercury lamps have not the 
intensity required. The radiation from incandescent lamps is low 
in actinic value. Even the Osram 15 volt projection lamp (100 hour 
life) gives poor results. Panchromatic film should be used with in- 
candescent lamps. 

The illumination of the slit can be accomplished in two ways: 
1. The diaphragm is covered with opal glass. A 10 ampere arc 
light with a mirror reflector is used as a light source. With this 
light an intensity of 3 cp. per sq. mm. resulted. The highest intensity 
obtained with the Argand burner used by Topler was 0.02 cp. per 
sq. mm. 



Aug., 1930] 



CINEMATOGRAPHY IN AUSTRIA 



225 



2. A light source is projected on the diaphragm to fill it with illumi- 
nation of high intensity. 

For this method a suitable lens must be used with the slit. As il- 
luminating and imaging lenses, objectives must be used which are 
well corrected for spherical and chromatic abberation. Astig- 
matism is of minor importance, as the slit is on the optic axis, and is 
small in size. The illuminating lens, BL, which serves to image the 
diaphragm, should be rather large, so that the phenomena being 
photographed cannot exceed its area. 

The form and position of the slit are of great importance to the sensi- 
tivity of the instrument. Both slit and diaphragm are of variable 
width. The slit is built like that of a spectrograph and the width 




FIG. 2. Circuit for spark photography. 

can be adjusted with a micrometer screw. The slit is mounted so it 
may be rotated by means of a worm and pinion. The reason for 
this type of slit is that there is usually a direction of maximum devia- 
tion in the striae being photographed, and it is necessary to orient the 
slit parallel with this direction in order to show the striae to best ad- 
vantage. The diaphragm, SB, must be large enough to cover the 
slit image. It must also be capable of rotation. 

The outside edges of the diaphragm, SB, must be exactly coinci- 
dent with the edges of the slit image. The diaphragm is composed 
of two strips, the edges of which are sharp and accurately parallel. 
One strip is fixed, while the other can be moved, the two remaining 
parallel. The whole equipment must be mounted on a solid floor 
free from vibration. The factor of greatest importance is that the 



226 



PAUL SCHROTT 



[J. S. M. P. . 



slit and condenser must be absolutely rigid as it is impossible to get 
good results otherwise. A single candle flame or bunsen burner serves 
as test object. These flames give typical striation phenomena. 
When the apparatus is used without any opal glass for diffusion, a 
taking speed of 500 pictures per second is not difficult. 

CINEMATOGRAPHY BY SPARK ILLUMINATION 

Dr. Franz Sochting has been working with photography by spark 
illumination. A method was developed for taking spark photographs 
by reflected light at such a frequency as would be of technical value 
for many purposes. It should be said that up till now all work 
with spark photography has been done by transmitted light, as only 

one per cent of the light required 
in the former case is needed for 
transmitted light photography. 

The wiring diagram of the ap- 
paratus is given in Fig. 2. A 1000 
volt, 5 KVA transformer acts 
through a water resistance, R, on a 
condenser, C, which is in shunt 
with the spark gap, F. Using the 
natural frequency of the circuit, 
50 cycles, if the spark gap is so ad- 
justed that a spark occurs at each 
half cycle, the resulting spark fre- 
quency, and hence the exposing 
rate, is 100 per second. By mak- 
ing the spark gap narrower, or 

decreasing the water resistance, more sparks occur per half period, 
but in an irregular way. Since, however, the time scale is determined 
by the velocity of the film, this factor may be disregarded. 

Test exposures were made>for spark regularity and for intensity of 
illumination. A matte black disk with white marks was mounted on 
the shaft of a 2-pole synchronous motor, running at 3000 rpm. The 
light from the spark was reflected to the disk by a parabolic mirror of 
80 mm. focal length and 240 mm. diameter. The rotating disk was 
photographed with an //4.5 Tessar on an ordinary plate having a 
speed of 16 to 17 Scheiner. Each spark gives a picture of the white 
mark, hence the intervals at which sparks occurred may be seen from 
the angles between the mark images. As the camera shutter was open 




FIG. 3. Test of spark regularity. 



Aug., 1930] CINEMATOGRAPHY IN AUSTRIA 227 

0.02 sec., and as one revolution of the disk takes 0.02 sec., the ex- 
posures for one cycle only were recorded. Figure 3 is an example of 





A B 

FIG. 4. Stream-line photography. 



PAUL, SCHROTT 



[J. S. M. P. . 



such a photograph. It will be seen that the mark images are sepa- 
rated into two groups of six each, in which each group represents 0.01 
sec. 

With the apparatus as described above, it was possible to record 
spark frequencies of 800 to 1000 per sec. The spark frequency has 
no effect on the exposure, which depends on the duration of each indi- 
vidual spark, about 0.00000005 sec., which is extremely short com- 
pared with attainable film velocities. No blurring due to movement 
of the film during exposure has ever been noticeable. Thus sparks 

can be used to photograph the flight of 
bullets or other rapid action. 

CINEMATOGRAPHY OF STREAM-LINE 
PHENOMENA 

Richard Katzmayr has described a new 
method for recording stream-line phe- 
nomena with the motion picture camera. A 
stream of water runs in a tray with a glass 
bottom. The tray is illuminated from be- 
low with diffused light. On the surface 
of the water are produced thin red colored 
streams of a solution having the same 
specific gravity as water. The camera is 
placed vertically above the tray. This red 
colored solution is supplied under pressure 
from a tube with a number of holes. The 
rate of flow is the same as that of the 
water. If a solid body is located on the 
surface of the water, the streams separate 
and show a change in stream lines. If 
the colored liquid is supplied continuously 

no motion is noticeable. (See Fig. 44.) By supplying the liquid 
intermittently, dotted lines which show progressive change are 
formed. (See Fig. 4B.) This is accomplished by placing in the 
supply tube from the tank of colored liquid a rubber tube on which 
an electric vibrator strikes twice a second. 

SURGICAL CINEMATOGRAPHY 

Motion picture recording has been used extensively in anatomical 
work. A special technic has been evolved by Prof. Pernkopf and 




FIG. 5. Section of an ana- 
tomical film. 



Aug., 1930] CINEMATOGRAPHY IN AUSTRIA 229 

his assistant Dr. Schmeidel; and several films useful for anatomical 
teaching have been made. 

In most cases, only the preparatory acts, and the dissecting of the 
individual anatomical structures need be recorded. By doing the 
work on cadavers which have been prepared before hand, much better 
results are obtained than with photography of surgical operations on 
living subjects. With cadavers, the opened and dissected structures 
are not covered with blood, which photographs black. The view can 
be taken from a short distance and any desired illumination can be 
used. The advantage of the anatomical film is that the pictures can 
be projected before a large audience, and as often as necessary. This 
results in a saving of time over repeated dissections, which can only 
be seen by the students nearest the demonstration. 

The method of dissection which is photographically recorded was 
worked out and introduced by Hochstetter in the Zweiten Anato- 
mischen Institute at the University of Vienna. Figure 5 is taken 
from a film so made. 

SLOW MOTION PHOTOGRAPHY OF MICROORGANISMS 

Dr. Otto Storch has done important work with slow motion photog- 
raphy on motion analysis of microorganisms. The "Askania" 
high speed camera was employed in this work. With this camera 
a speed of 100 to 120 pictures per second is attainable. The out- 
standing feature which makes this camera very useful for microscopic 
work is the finder, which focuses on the film and gives four to eight 
diameters magnification. The image is erect and can be observed 
before and during the exposure. All the light from the subject is 
focused on the film; there is no loss since a prism or a half-silvered 
mirror is not used. 

The second part of the equipment, the microscopic apparatus, was 
built by the Wiener Optischen Werke (C. Reichert) in Vienna. Two 
matters of great importance required attention in the construction of 
this equipment: (1) All the necessary movements should be capable 
of adjustment from a position comfortable for the operator. (2) 
The microscopic subject must always be in view. In other words, the 
operator must observe the subject continuously. He must be able 
to adjust the table height, to focus, and to start and stop the camera at 
the required moment. The fulfillment of these conditions is impor- 
tant, as biological subjects demand great patience and skill on the 
part of the operator in preparing them suitably for photography. 



26 PAUL SCHROTT [J. S. M. P. & 

When the preparation is in place, the adjustment of the microscope 
and camera must be accomplished quickly and easily. At this stage 
the operator must watch the subject in the finder, and must be able 
to start the camera at the proper time. The subject is naturally in- 
tractable and the high intensity of the light used makes it just so 
much worse. Adjustment for using the microscope either horizon- 
tally or vertically has been provided. 

The apparatus is adaptable for macrophotography (X20 to X30 
diameters), using enlarging photographic objectives ("Mikropolars," 




FIG. 6. Photomicrographic equipment. 

made by C. Reichert). The specimens are placed in a cell and may 
move in a vertical plane when the axis of the objective is horizontal 
and are held in a glass tray, in a horizontal plane when the axis is 
vertical. 

At the present time the equipment is used only with transmitted 
light, but arrangements are being made for work with reflected light. 

The camera position is fixed, irrespective of the microscope arrange- 
ment, and the finder is always at eye level. The camera is mounted 
on a massive arm which can be swung horizontally. (See Fig 6.) 
By this arrangement the camera can be easily shifted away from 



Aug., 1930] CINEMATOGRAPHY IN AUSTRIA 231 

the microscopic apparatus, and all operations such as loading and 
unloading can be accomplished easily without disturbing the rest of 
the set-up. Changes in the microscopic equipment lenses, etc., can 
be accomplished quickly. 

The optical equipment is mounted on a massive adjustable bench 
supported on the floor. By supporting the camera from the wall and 
the optical bench from the floor, no vibration will be transmitted 
from the camera to the bench. The camera itself is very steady on its 
support, and no lack of definition has been noticed. The excellent 
definition may be partially due to the high speed at which the pictures 
are taken (usually over 100 frames per second) and to the relatively 
short exposures given (from 1/500 to 1/3000 sec.). 

The camera remains in a horizontal position, whether the micro- 
scope is in a horizontal or vertical position. Experiments were made 
with the camera in a vertical position, but this arrangement did not 
prove feasible. Not only was the finder position too high, but no 
simple way could be found to mount the camera on a steady support. 

When using the microscope vertically it is necessary to mount a 
prism between the ocular and the camera. This can be done without 
loss of light or other disadvantages. During exposure the camera and 
microscope are joined by light-tight tubes, which are not in contact, 
thus avoiding transmission of vibration. By having the optical 
bench adjustable for height, and having the camera remain in a posi- 
tion convenient for the operator, it is possible to mount on the bench 
various optical systems of different heights, and still bring the optic 
axis level with that of the camera. Having the camera movable is 
a great advantage, as it may be swung out of the way when changes 
must be made in the optical equipment. 

For photography with the microscope horizontal, the microscope 
is placed on a table of such height that the beam from the arc lamp is 
axial with the microscope condenser, and goes directly through to 
the camera frame. 

For the macrographic subject a separate table is provided which 
may be raised, lowered, or moved sideways. The subjects are placed 
in a cell in which is a movable glass wall which may be brought as 
close as */2 mm. to the side of the cell, making it possible to keep the 
subject continually in focus without interfering with natural move- 
ment. This type of cell has the advantage that water can be run 
through it in quantity, hence it will not heat up during the short time 
required for the preparation and photography of the subject. This 



232 PAUL SCHROTT [j. s. M. p. B. 

micro-aquarium also was constructed by the Optischen Werken 
(C. Reichert). In the set-up, for photomicrography a spectacle 
lens is used for a condenser to concentrate the light from the arc 
on the objective, while for photography with the microscope the 
Abbe condenser is mounted in the usual way on the substage. 

A Goerz 25 ampere arc light built into a lamphouse with a condenser 
is used on d.c. The light is very intense and highly actinic, so that 
even with high magnification, short exposures are possible. When 
using the "Mikropolar" (relative aperture //4) exposures of 1/2880 
sec. (120 frames per second with a shutter opening of 15) were given 
and fully exposed negatives were obtained. 

With a high microscopic magnification (Reichert 4 mm. apochro- 
mat, compensating ocular, 4X) exposure times as short as Vsoo sec. 
give full exposure. These short exposures make it possible to show 
clearly the fastest motion of the microorganism, and very little loss 
of sharpness results. 

Slow motion pictures of the living organism offer the greatest dif- 
ficulty. The heat from the arc light is great enough to kill the or- 
ganism in a very short time. For illumination in this case the follow- 
ing system was worked out by the writer and more research work is in 
progress at present. In front of the arc light is placed a large cell 
with running water. (See Fig. 6.) This alone proved insufficient so 
that the following artifice is employed. The arc is connected with a 
rheostat and while focusing and preparing for exposure, the current 
is cut down to 5 amperes. A light absorbing green filter is also placed 
in front of the water cell, cutting down the heat considerably. It 
is now possible to focus the camera and adjust the optical equipment 
for any required time without damage to the subject to be photo- 
graphed when the equipment is adjusted. After the subject has 
been focused on the film, and the shutter opening has been set, the 
assistant removes the filter and at the same time runs the arc current 
up to 25 amperes. The camera is started immediately and during the 
actual time consumed in taking the picture no harm is done to the 
subject. For slow motion work, 100 to 120 frames per second can be 
exposed, which amounts to 30 to 40 meters of negative material in 
15 to 20 seconds. 

A few remarks should be made regarding the scientific use of the 
photographs. The first step is to have a positive made, and run 
through a projector several times at slow speed. A small home pro- 
jector, of which there are many makes available and which are safe 



Aug., 1930] CINEMATOGRAPHY IN AUSTRIA 233 

when handled with care, is suitable for laboratory use. In scientific 
work it is necessary to view the motion of the organism repeatedly 
and this can be done best by the use of a loop. The projector 
should also be equipped with a single frame attachment. 

It was found by experience that the best scientific information 
could be gained when the frames were printed by contact on glossy 
paper strips. Strips are cut into single pictures and arranged in 




* t t 



9 f . * 



FIG. 7. Diaptomus denticornis. Enlargements from consecutive photo- 
graphs from a film taken at 120 frames per second. Stretching of the an- 
tennae after a jump. 

sequence on a sheet of paper. Such copies (Fig. 7) are very con- 
venient in studying the subject. 

PRODUCTION OF MOTION PICTURE EQUIPMENT IN AUSTRIA 

No projectors are made in Austria, but a very satisfactory camera 
has been placed on the market by the firm of Castagna Co. G. m. b. H. 
(Fig. 8). A light metal is used for the camera housing. All fast 
moving parts run in roller bearings. The camera is built on an en- 
tirely new plan, except for the pull-down mechanism, which is of 



234 



PAUL SCHROTT 



[J. S. M. p. E. 



the Lumiere type. Four lenses are mounted on a turret. Any lens 
from 35 mm. up to a telephoto lens can be used. The turret can be 
rotated slightly to raise or lower the lens, which eliminates moving the 
whole camera for the desired result. Focusing can be done directly 
on the film with a telescope, or by turning the lens turret through 
180 degrees and focusing on a ground glass with a prism. The camera 
front can be swung open, and the lens turret and pressure gate are 
built into it, thus eliminating any error in focusing. The patented 
shutter is also built into the front. This shutter which is of a new 
type was designed by Dr. Julius Urbanek, of the staff of the Technical 




FIG. 8. Castagna camera. 

High School at Vienna. It is actuated by a double differential gear. 
The special feature of this shutter is that it can be closed in 3, 5, or 
8 turns, irrespective of the sector setting. 

In changing the rate from eight to a single frame per turn, the 
camera crank remains in the same position. The film magazines 
are made from a light metal and have a fool-proof aperture, 
not lined with velvet. The tension of the take-up can be ad- 
justed from the outside of the camera if required while operating. 
The following equipment is incorporated in the back of the camera: 
footage and single frame counter, finder, a lever to control the ten- 
sion of the supply magazine, a lever to adjust the shutter opening, 



Aug., 1930] 



CINEMATOGRAPHY IN AUSTRIA 



235 



and a scale to show the shutter opening in degrees. The control of 
the automatic dissolve (3, 5, or 8 turns) is also handled from the rear. 
A lever to effect the automatic opening or closing of the shutter, and 
the film punch are placed on top of the camera. 

An invention of considerable value in running arc lamps for motion 
picture projection is the Rosenberg cross-field generator, manufac- 
tured by "Elin" a. g. fiir Elektrische Industrie, Vienna- Weiz. This 
generator makes possible the running of arc lights without any rheo- 
stat. The arc is connected directly to the generator terminals, 
and the voltage and current are self regulating. The principles of 
the machine, which was originally built for arc welding, are as follows: 




\ 



FIG. 9. Rosenberg cross-field 
generator. 



FIG. 10. Voltage current rela- 
tions for the Rosenberg generator 
with different pole piece settings. 



The commutator has four brushes (Fig. 9) of which two, bi and b z , 
are short circuited. PI and Pi are the magnetic poles, B\ and B 2 are 
the main brushes. As a result of residual magnetism, when the arma- 
ture is rotated, a low potential is induced between the short-circuited 
brushes, and a high current is generated in the armature. Hence 
there exists in the armature a strong magnetic field which is in the 
direction of the brushes, bi and b z . In this field, which the armature 
itself generates, a high potential is generated at the brushes, BI and 
BI. When the outer circuit is closed, a current flows through the 
armature and through the exciting coils of the poles, PI and PI. There 
results a magnetic field in the direction, PiP2, and an armature field in 



236 PAUL SCHROTT 

the same direction. The two fields are, however, opposed. But 
the field, P\Pz, is the more powerful, and the current is increased. If 
the current is very great, because of the unusual form of the iron 
poles, PI, Pa, of small cross section, saturation of the iron occurs, the 
field strength of the poles increases slowly, but the field of the arma- 
ture goes up rapidly since both oppose each other, the resulting field 
strength becomes weaker, the potential at the brushes, B\ and B 2 , 
grows less, and the current is lowered. The poles, PI and PZ, can be 
screwed out so that the cross section of iron is made smaller. It is 
thus possible to regulate the maximum current strength. The arc 
light is connected to BI and B 2 . On striking the arc, a short circuit 
results, but only a small current is produced. As the carbons sepa- 
rate, the potential adjusts itself according to the strength of the cur- 
rent. Figure 10 shows the voltage-current curves of such a dynamo 
for different adjustments of the pole pieces. As we see, by this pro- 
cedure, the characteristic action of the carbons is stable, as an increase 
in current causes a decrease in potential. 

Advantages of the Rosenberg generator are as follows: 

1. All the accessory apparatus in the arc lamp circuit can be elimi- 
nated, regulators, rheostat, voltmeter, fuses, etc. 

2. The efficiency is about 20 per cent higher than that of the usual 
equipment with the stabilizing rheostat. 

3. In the case of a short circuit, the current is only slightly higher 
than that usually drawn, hence the fire hazard is eliminated. 

4. The potential for open circuit is not dangerous. 

5. The generator voltage regulates itself automatically in accord- 
ance with the length of arc. 



ABSTRACTS 



The Editorial Office will welcome contributions of abstracts and book reviews 
from members and subscribers. Contributors to this section are urged to give 
correct and complete details regarding the reference. Items which should be 
included in abstracts are: 

Title of article 

Name of author as it appears on the article 

Name of periodical and volume number 

Date and number of issue 

Page on which the reference is to be found 
In book reviews, the following data should be given: 

Title of book 

Name of author as it appears on the title page 

Name of publishing company 

Date of publication 

Edition 

Number of pages and number of illustrations 

The customary practice of initialing abstracts and reviews will be followed. 
Contributors to this issue are as follows: Clifton Tuttle, and the Monthly 
Abstract Bulletin of the Kodak Research Laboratories. 

Ninety Million Feet of Color Photography Set as Colorcraft Yearly Output. 
D. Fox. Ex. Herald World, 98, 26, Jan. 4, 1930. Twelve developing and dyeing 
units having a capacity of 23 feet of film per minute are being installed in the 
Long Island laboratory of the Colorcraft Corporation. Two negatives are used 
in exposing the film and a double coated positive for making the prints which are 
subsequently dyed. The technical description given is very vague. Kodak 
Abstr. Bull. 

Harriscolor Perfects Its Process: Adds Equipment. Ex. Herald World, 98, 
21, Feb. 1, 1930; Mot. Pict. News, 41, 72, Feb. 8, 1930. A trade note states that 
equipment for the three-color process known as Harriscolor has been installed to 
take care of 15 million feet of prints during the next six months. No technical 
details are given though it is stated that the prints are made on a single emulsion 
film. Kodak Abstr. Bull. 

Problem of Distortion in Sound Film Reproduction. C. O. BROWNE. Experi- 
mental Wireless, 8, 71, February, 1930. The frequency characteristics of a sound 
film recording and reproducing system are discussed with a view to producing a 
level combined frequency response. Various recorders, and the methods by 
which their frequency responses can be brought into line with that of the repro- 
ducer, are described briefly. Correction can also be made for recording and re- 
producing slit attenuation. A recording system producing a twin wave track 
variable width record is described in some detail. The essential points of variable 
density recording are considered. Kodak Abstr. Bull. 

237 



238 ABSTRACTS [J. S. M. p. E. 

Electroacoustic Transmission Systems with Special Reference to Distant Te- 
lephony and Sound Films. F. LUSCHEN. Elektrotech. Z., 50, 1693, Nov. 21, 1929. 
Electric filters are discussed, and their use in correcting the damping and phase 
characteristics of the recording and reproducing units is demonstrated. Fre- 
quency amplitude characteristics of different types of sounds are shown graphi- 
cally. Kodak Abstr. Bull. 

Electroacoustic Transmission Systems with Special Reference to Distant Te- 
lephony and Sound Films. F. LUSCHEN. Elektrotech. Z., 50, 1728, Nov. 28, 1929. 
Amplitude characteristics are treated and effects of nonlinear distortion shown. 
Various systems of recording and reproducing are described in some detail. 
Kodak Abtsr. Bull. 

Running the Talkies. XX. Symplaphone. R. H. CRICKS. Kinemat. 
Weekly, 155, 64, Jan. 23, 1930. The synchronizer is a direct driven unit coupled 
to the projector. British Thomson-Houston pickups are used. The novel sys- 
tem of speed control and the amplifying unit are described and criticized. Kodak 
Abstr. Bull. 

Running the Talkies. XXI. British Thomson-Houston. R. H. CRICKS. 
Kinemat. Weekly, 157, 71, March 13, 1930. A description is given of the British 
Thomson-Houston projection equipment for sound films. Kodak Abstr. Bull. 

Making Sound Films. V. Some Recording Problems and Principles. T. T. 
BAKER. Kinemat. Weekly, 156, 60, Feb. 13, 1930. The principles involved in 
methods of sound recording by variable density or variable width are outlined. 
Kodak Abstr. Bull. 

Synchronizing Record Starts. A. B. REEVES. Mot. Pict. Projectionist, 3, 
15, December, 1929. The author has worked out a method whereby the needle 
of the pickup device may be replaced into the proper groove of the record when 
starting the projector to insure synchronizing in case some film has been de- 
stroyed. A label pasted or stamped in the center of the reel contains a scale indi- 
cating the number of frames per complete turn of the record. There is also a 
table indicating the number of turns of the disk and the number of frames 
(counted on the scale) it is necessary to correct for in order to synchronize the 
disk for the loss of a known number of feet of film. Kodak Abstr. Bull. 

Modern French Factory. G. M. COISSAC. Cineopse, 12, 47, January, 1930. 
An account is given of the most important products of the ^tablissements Andre 
Debrie. The adaptation of their camera "Parvo," model L, for the taking of 
sound pictures has been effected, and the former printer has been modified so that 
sound and pictures may be printed simultaneously. A new apparatus for making 
animated drawings has recently been perfected. The equipment built for micro- 
cinematography is notable in that exposures are made automatically at the de- 
sired rate, while the opaque sector of the shutter is only 60 degrees, so that a 
minimum of light may be used on sensitive specimens. Special effects, such as 
enlargements, reductions, fade-outs, and double exposures are obtained by print- 
ing with the "Truca." Finally, mention is made of a recent invention which 
records longitudinally on motion picture film a continuous image of a freight 
train as it passes the camera. Kodak Abstr. Bull. 

Measurements on Sound Absorbing Materials. E. MEYER AND P. JUST. 
Elektrotech. Z., 51, 97, Jan. 16, 1930. A small model room was set up and the 
reverberation time measured with an oscillator driven loud speaker as source and 



Aug., 1930] ABSTRACTS 239 

a microphone-rectifier-galvanometer arrangement as the measuring device. A 
portion of the wall was covered with a sound absorbing material and the rever- 
beration time again measured. The two reverberation values made possible the 
calculation of the absorption coefficient of the material. Kodak Abstr. Bull. 

Protection of Film: Methods of Preventing Surface Marking. Bioscope 
(Mod. Cinema Technique), 82, March 5, 1930, p. iii. In the Henderson method 
of film treatment the films are not coated, but are impregnated with the preserv- 
ing solution. Film treated by the Henderson method may subsequently be 
freed from oil or dirt by means of a dry cloth or damp leather, without the use of 
spirit or cleaning solutions such as are necessary for untreated films. The treat- 
ment may be applied not only to new films, but to the reconditioning of old 
copies. Kodak Abstr. Bull. 

Making Sound Film. IV. Frequency Range. T. T. BAKER. Kinemat. 
Weekly, 156, 67, Feb. 6, 1930. The importance of the grain size of the photo- 
graphic emulsion in sound recording is explained. An apparatus is described by 
means of which, it is stated, the maximum number of sound waves per second 
which a film will record when traveling at a given rate can be determined. Kodak 
Abstr. Bull. 

Making Sound Films. III. Sensitometric Tests. T. T. BAKER. Kinemat. 
Weekly, 155, 67, Jan. 16, 1930. The significance of sensitometric curves and of 
gamma-time curves is explained, and image quality (graininess, fog, scratches, 
and uneven development) and its examination are discussed. The following 
formula is given for a fine grain developer in which tribasic sodium phosphate is 
the accelerating alkali: 

Metol 4 grains 

Hydroquinone 10 grains 

Sodium sulfite (crystal) 400 grains 

Tribasic sodium phosphate 1 grain 

Potassium bromide 2 grains 

Water to 2000 cc. 

(In the above paper the weights are called "grains." This appears to be a mis- 
print for "grams.") Kodak Abstr. Bull. 

Lighting the Studio: Use of the Incandescent Unit. Kinemat. Weekly, 155, 
64, Feb. 20, 1930. A summary of a paper read by W. C. Villiers before the 
Illuminating Engineering Society is given. For general lighting, 1500 watt 
lamps are becoming standard. They are arranged in banks, the largest of which 
take about 1800 kilowatts and are fitted with reflectors of aluminum. For spot 
lighting, 3000 watt lamps fitted with parabolic silvered glass mirrors give the 
best results, while for sun lighting special 10 kilowatt gas filled lamps have been 
constructed with various devices for cooling the bulb and for avoiding the ob- 
scuration of the walls by metallic deposition. Kodak Abstr. Bull. 

The Cinema and Children. Intern. Rev. Educational Cinemat., 2, 43, January, 
1930. This is a report and comment on the results of a questionnaire on the 
cinema submitted to Russian children by Elkin. The children were classified, 
most of them being either workers' children or waifs. The cinema was the 
favorite amusement of most of these children. Adventure films were preferred. 
Kodak Abstr. Bull. 



240 ABSTRACTS 

Function of the Picture in Science Instruction. A. HORN. Ed. Screen, 9, 75, 
March, 1930. The motion picture may be a substitute for classroom demonstra- 
tion experiment, giving better visibility of technical skill. Science courses are 
becoming an organized study of environment which is facilitated by motion 
pictures. Kodak Abstr. Bull. 

University Film Foundation of Harvard University. Science, 71, 381, April 
11, 1930. The University Film Foundation has been established at Harvard 
University by the aid of John D. Rockefeller, Jr. A sound proof studio, sound- 
on-film and sound-on-disk recording equipment, a processing laboratory for 
standard and amateur standard film and editorial rooms are provided. A 
number of scientific films have already been produced, and its is planned to make 
sound pictures of eminent professors and others as historical records. Kodak 
Abstr. Bull. 

Evolution of Sound Pictures. M. CRAWFORD. Intern. Phot. Bull., 3, 20, 
March, 1930. A historical summary from 1878 to the present day of inventions 
and devices used to record sound in conjunction with motion pictures. Among 
others, the work of Demeny, Bdison, Gaumont, Lauste, De Forest, Case, and 
Hoxie is mentioned. Credit is given to Lauste for the invention of the sound- 
on-film record and to De Forest for making it a commercial success. Recently, 
Madelar has developed a method of recording on the base side of film by means 
of a diamond stylus producing a sound record similar to the sound-on-disk 
record. The picture is photographed as usual on the opposite side. A some- 
what similar method was worked out by White, of the Edison Company, in 1903 
or 1904. Kodak Abstr. Bull. 

Present Position of Sound Film. E. STENGER. Camera (Luzerri), 8, 113, 
November, 1929. A brief history of photography, cinematography, and sound 
pictures is presented. An outline is given of the following three systems of 
sound reproduction: (1) the phonograph record system; (2) the film sound 
record using a light-sensitive cell for reproduction; (3) the magnetized steel band 
method. The changes brought about in studio technic are described. Kodak 
Abstr. Bull. 

Wide Screen by New Method (Victor Talking Machine Co.). Bioscope 
(Mod. Cinema Technique], 82, Jan. 29, 1930, p. i. A lens system fitted to the 
camera condenses the lateral range of the latter about three times, standard film 
being used. In the projection apparatus the image is expanded to its proper 
dimensions. Thus a wider sound track is made possible without the risk of 
film buckling which is experienced with wide film. The device can be fitted to 
the ordinary projector for about 25 dollars. Kodak Abstr. Bull. 

Wide Film Problems. R. H. CRICKS. Kinemat. Weekly, 156, 67, Feb. 13, 
1930. It is contended that the only real advantage of wide film, namely, im- 
provement with regard to the emulsion grain size problem, does not justify the 
enormous expense of new projection apparatus and new screens in every cinema. 
A simple and less expensive method of overcoming the grain size problem would 
be to photograph on double width negative material, afterwards printing on 
standard size slow speed, fine grain positive stock. 'Kodak Abstr. Bull. 



BOOK REVIEWS 

Sound Pictures and Trouble Shooters Manual. JAMES R. CAMERON AND 
JOHN F. RYDER. Cameron Publishing Co., Manhattan Beach, Brooklyn, N. Y., 
1930, 1120 pp., $7.50. The first part of the book is devoted to general electricity, 
vacuum tubes, and vacuum tube circuits. The material contained in these 
pages is not advanced enough to be very instructive to anyone familiar with the 
field, and careless wording and proof reading errors would make the subject 
matter unnecessarily difficult for the conscientious beginner. There are a few 
chapters on recording which may be interesting to the lay reader. Projection 
equipment, its maintenance and operation, is treated quite thoroughly; and we 
assume that the information given agrees with that furnished by the manufacturer 
of the apparatus. There are a hundred pages which treat of "trouble shooting" 
and which should enable the reader to trace down trouble in theater reproducing 
equipment. C. M. T. 

Agfa Kine Handbook. Parts I-IV. The Agfa Kine Handbook, in four parts, 
describes the manufacture and use of the products of the Agfa film factory, 
which are related to the motion picture industry. Part I includes a brief history 
of the Agfa Company, a description of the manufacture of raw motion picture 
film and instructions for the handling of film. Part II explains the various 
grades of motion picture negative film which are suitable for different types of 
photography, such as ordinary and color motion picture work, aerial photog- 
raphy, and photography in the tropics. Formulas of developers and fixing 
baths suitable for processing the films are given. Part III deals with the proper- 
ties of the positive motion picture film. General instructions are given for de- 
veloping, fixing, drying, toning, and tinting of this film. Part IV contains speci- 
mens of tinted and toned positive film and specimens which show the effects of 
various treatments on the quality of negative film. Kodak Abstr. Bull. 



241 



SOCIETY OF MOTION PICTURE 
ENGINEERS 

OFFICERS 

President 
J. I. CRABTREE, Eastman Kodak Co., Rochester, New York 

Past President 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

Vice-Presidents 

H. P. GAGS, Corning Glass Works, Corning, N. Y. 
K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 

Secretary 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

Treasurer 
W. C. HUB BARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

Board of Governors 

H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Roches- 
ter, N. Y. 

J. I. CRABTREE, Research Laboratory, Eastman Kodak Co., Roches- 
ter, N. Y. 

J. A. DUBRAY, Bell & Howell Co., 1801-1815 Larchmont Ave., Chi- 
cago, 111. 

H. P. GAGE, Corning Glass Works, Corning, N. Y. 

K. C. D. HICKMAN, Research Laboratory, Eastman Kodak Co., 
Rochester, N. Y. 

W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood 
Blvd., Los Angeles, Calif. 

P. MOLE, Mole-Richardson, Inc., 941 N. Sycamore Ave., Holly- 
wood, Calif. 

M. W. PALMER, Paramount-Famous-Lasky, Inc., 6th & Pierce Aves., 
Long Island City, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

S. ROWSON, Ideal Films, Ltd., 76 Wardour St., London, W. 1, England 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 
242 



243 



J. G. CAPSTAFF 



J. W. COFFMAN 



E. ADAMS 

C. L. GREGORY 



COMMITTEES 
1929-1930 

Color 

W. V. D. KELLEY, Chairman 

W. T. CRESPINBL F. K. IVBS 

Convention 

W. C. KUNZMANN, Chairman 

W. C. HUBBARD M. W. PALMER 

Historical Committee 

F. J. WILSTACH Chairman 

C. F. JENKINS A. S. NEWMAN 

O. NELSON T. RAMSAYE 



Journal 

L. A. JONES, Chairman 

J. W. COFFMAN H. T. COWLING W. C. HUBBARD 

J. H. KURLANDER 

Membership and Subscription 

H. T. COWLING, Chairman 

C. BARRELL J. DEFRENES B. E. NORRISH 

J. W. BOYLE E. R. GEIB I. ROSEMAN 

W. H. CARSON D. E. HYNDMAN E. C. SCHMITZ 

W. CLARK J. KLENKE J. L. SPENCE 

It. W. DAVEE M. L. MISTRY F. ZUCKER 

Papers 

J. W. COFFMAN, Chairman 

M. C. BATSEL C. R. HANNA G. E. MATHER 

F. J. CADENAS K. C. D. HICKMAN R. F. NICHOLSON 

J. A. DUB RAY E. HUSE J. B. TAYLOR 

O. M. GLUNT D. E. HYNDMAN 



Progress 

G. E. MATTHEWS, Chairman 
M. ABRIBAT J. B. ENGL 

J. A. BALL R. E. FARNHAM 

J. BOOLSKY H. B. FRANKLIN 

W. CLARK E. R. GEIB 

K. GEYER 



A. C. HARDY 
R. C. HUBBARD 
G. F. RACKETT 
S. K. WOLF 



244 



COMMITTEES 
Projection 



[J. S. M. P. E. 



H. W. DREYER 
G. C. EDWARDS 
P. H. EVANS 
T. FAULKNER 
J. H. GOLDBERG 



L. M. TOWNSEND, Chairman 

C. GREENE R. MIEHLING 

H. GRIFFIN W. B. RAYTON 

N. M. LA?ORTE F. H. RICHARDS 
R. H. MCCULLOUGH H. B. SANTEE 
W. A. MCNAIR D. F. WHITING 



F. C. BADGLEY 



Publicity 
W. WHITMORE, Chairman 

B. w. DEPUE 
G. E. MATTHEWS 
G. F. RACKETT 



O. A. Ross 



J. W. COFFMAN 



Solicitation 
E. P. CURTIS, Chairman 



E. A. WILLIFORD 



Standards and Nomenclature 



M. C. BATSEL 
W. H. CARSON 
L. W. DAVEE 

A. DEBRIE 
L. DEFOREST 
J. A. DUBRAY 
E. W. ENGSTROM 



A. C. HARDY, Chairman 
P. H. EVANS 
R. E. FARNHAM 
H. GRIFFIN 
R. C. HUBBARD 
L. A. JONES 
N. M. LAPORTE 
G. MITCHELL 
W. P. POWERS 



G. F. RACKETT 
W. B. RAYTON 
V. B. SEASE 
T. E. SHEA 
J. P. SPENCE 
E. I. SPONABLE 
L. T. TROLAND 



L. J. BUTTOLPH 



Studio Lighting 

A. C. DOWNES, Chairman 

R. E. FARNHAM M. W. PALMER 
K. C. D. HICKMAN 



J. C. AALBERG 
F. A. BENFORD 
A. C. DOWNES 



Theater Lighting 

C. E. EGELER, Chairman 
F. FALGE 
R. E. FARNHAM 



C. GREENE 
E. HUSE 
L. A. JONES 



Aug., 1930] COMMITTEES 245 

CHICAGO SECTION 

J. A. DUBRAY, Chairman O. F. SPAHR, Manager 

J. E. JENKINS, Sec.-Treas. O. B. DsPuE, Manager 



LONDON SECTION 

SIMON ROWSON, Chairman 

A. NEWMAN, Vice-Chairman PAUL KIMBERLEY, Manager 
L. EVELEIGH, Secretary ALAN WILLIAMSON, Manager 

H. WOOD, Treasurer WILLIAM VINTEN, Manager 

NEW YORK SECTION 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 



PACIFIC COAST SECTION 

P. MOLE, Chairman C. DUNNING, Manager 

G. F. RACKETT, Sec.-Treas. E. HUSE, Manager 

Membership Committee 

J. COURCIER, Chairman 
E. JEWELL 

Papers and Programs 
E. HUSE, Chairman 



PRESIDENTIAL ADDRESS 

It is a pleasure to welcome you to this, the twenty-ninth convention 
of the Society, and especially those who are attending for the first 
time. In former days, when the Society was not so large, it was pos- 
sible for your chief executive to know each member personally but 
with our present membership of about 800, this is not possible. How- 
ever, I shall endeavor to meet every new member attending this con- 
vention. 

I think I can say without fear of contradiction that the Society 
has made great progress since our last convention at Toronto. Per- 
haps we can get a measure of this progress by considering to what 
extent we have been fulfilling the objects of our Society as set forth 
in our constitution. These objects are as follows: 

(1) Advancement in the theory and practice of motion picture 
engineering and the allied arts and sciences. I think that the large 
number, and high technical and scientific merit of the papers to 
be presented at this meeting are ample assurance of this, while the 
increasing eagerness on the part of the trade and technical press to 
publish our technical papers is an index of their value to the industry. 

(2) The standardization of the mechanisms and practices employed 
in the motion picture arts and sciences. One of the most difficult 
problems in standardization ever undertaken by this Society has 
been that of the determination of dimensional standards for wide 
film. The Society was fortunate in obtaining Professor A. C. Hardy 
of the Massachusetts Institute of Technology to accept the chairman- 
ship of the Standards and Nomenclature Committee, and a subcom- 
mittee under the chairmanship of Mr. M. C. Batsel and consisting 
of the chief engineers of all the interested producing organizations 
has been meeting at bi-weekly intervals during the past three months, 
wrestling with this problem. Although at this moment no definite 
standard has been arrived at, the prospects of an early agreement are 
extremely promising. 

At any rate, the Society has rendered a valuable service to the 
industry by virtue of preventing the producers from plunging blindly 
into this new development in the absence of a suitable standard 
and the danger of the recurrence of the chaos which prevailed in 
246 



PRESIDENTIAL ADDRESS 247 

the early history of the film business, when each producer used a 
different size film, I believe, has been averted. The committee is- 
dealing with many other standards and has published a booklet 
which includes all the standards adopted by the Society to date and 
which have been approved by the American Engineering Standards 
Committee. 

(3) The dissemination of knowledge by publication. Our So- 
ciety took a great step forward when it decided to publish the scien- 
tific papers presented at our conventions in a monthly JOURNAL in- 
stead of in quarterly Transactions. By this means, papers are pub- 
lished promptly and the more important ones are made available with 
a minimum loss of time after presentation while it is now possible 
for the Society to publish contributed papers not presented at con- 
ventions, translations of papers in foreign languages, abstracts, book 
reviews, patent abstracts, and Society notes. 

The value of the Society to the industry is largely determined by 
the extent to which the industry makes use of the scientific informa- 
tion which we make available and this is determined by its degree of 
distribution. Our JOURNAL is now reaching a much larger number of 
technicians than was formerly the case with our Transactions and 
the industry is benefiting accordingly. 

One of the most pressing needs of the Society is a focal point in the 
form of permanent headquarters with clerical assistants to take care 
of the routine work of the Secretary and Treasurer. Through the 
generosity of our sustaining members, sufficient funds are now avail- 
able for such headquarters and a paid editor for the JOURNAL. 

The increasing value of the Society to our members has been mani- 
fest by the formation of a local section in New York City in addition 
to those now existing in London and Hollywood. Yesterday the 
Board of Governors also approved the formation of a section of the 
Society in Chicago. Such sections permit a more thorough discussion 
of the many perplexing technical problems now facing the industry 
and afford a means of discussing papers of immediate interest. The 
sections have already contributed a number of valuable papers to our 
JOURNAL. 

Three new committees have been appointed as follows: The Color 
Committee under the chairmanship of William V. D. Kelley, which 
will keep the members informed of progress in this important field; 
the Historical Committee under the chairmanship of Frank J. Wil- 
stach, which has made investigations on the early history of the in- 



248 PRESIDENTIAL ADDRESS [J. S. M. P. E. 

dustry and is collecting valuable films and apparatus which are to 
be placed in a suitable depository; the Solicitations Committee under 
the chairmanship of Mr. E. P. Curtis, which has performed a service 
to the Society by persuading the various manufacturing and producing 
interests to bear their fair share of the burden of the work of conduct- 
ing the business of the Society by contributing financially through the 
medium of sustaining memberships. The Constitution and By- 
Laws Committee under the chairmanship of W. C. Hubbard has re- 
commended a modification of the by-laws so as to bring them in 
conformity with the increasing size of the Society. 

The Society owes a special debt to Mr. L. A. Jones and the JOUR- 
NAL Committee for conducting the Herculean task of publishing 
the JOURNAL with consistent promptness. This committee has issued 
three booklets which are available to members, namely (a) List of 
Members, (6) Instructions to Authors, and (c) Standards Adopted 
by the Society. 

One of the most important technical aspects of this great industry 
is that of reproducing sound satisfactorily and the placing of the 
best possible picture on the screen from the film supplied by the pro- 
ducer. Our Projection Committee is investigating this great problem 
of getting improved sound and picture quality with an enthusiasm 
worthy of emulation. To give you some idea of this enthusiasm, the 
chief engineer of one of the large producing organizations sustained 
an injury the day previous to a meeting of the Projection Committee, 
but rather than miss the meeting he attended on crutches. 

The Publicity Committee has consistently secured space in the 
trade papers. The Society has frequently obtained front page 
notices. A joint meeting of the Publicity and Membership and Sub- 
scription Committees was held in Schenectady on March 4th to 
outline plans for the extensive arrangements for publicity which 
have been made for this convention. 

The resignation of our former secretary, Mr. R. S. Burnap, caused 
a deep feeling of regret but the Society has been fortunate in securing 
the services of Mr. J. H. Kurlander to continue this office and he is 
well known to most of you. 

The future activities of the Society must be focussed on the one 
object of rendering increasing service to the industry. The acquisi- 
tion of a paid editor with permanent headquarters and organized as- 
sistants will contribute materially to this end. 

Of the pressing technical problems, that of getting better sound 



Aug., 1930] PRESIDENTIAL ADDRESS 249 

both on and out of the film or wax record is the most important. 
The marvelous realism of the sound being reproduced in one of the 
smaller Broadway theaters by way of reproduction of the voice of a 
Metropolitan star is a sufficient indication that with existing equip- 
ment it is possible to record and reproduce sound with a much greater 
degree of realism than is manifest in many theaters today. One of 
the aspects of this problem is that of the education of the projectionist 
and theater manager. Projection has become so much more impor- 
tant and difficult and the projectionist must become so much more 
expert. 

I feel sure that our Society will continue to participate increasingly 
in the advancement of scientific knowledge and the improvement of 
the realism of the motion picture, and thereby contribute to the educa- 
tion and enjoyment of the vast army of motion picture patrons 
throughout the world. 

J. I. CRABTREE, President 



THE BANQUET 

Wardman Park Hotel, Washington, D. C. 
May 7, 1930 



SPEECHES DELIVERED THROUGH THE MEDIUM OF THE TALKING 

FILM 



Mr. Chairman, Ladies, and Gentlemen: 

It gives me a great deal of pleasure to bring to you tonight the 
greetings and the congratulations of the Academy of Motion Pic- 
ture Arts and Sciences in Hollywood and to congratulate you on the 
tremendous strides of achievement that you have been responsible 
for within the last two years. 

When I first started making a talking picture only a year and a 
half ago we were terribly tied up, the directors couldn't move, the 
sound engineers would tell us how our people must turn, how they 
must speak, where they must go, and sometimes even what they must 
do. They soon got the idea, however, that that couldn't go on and 
still be an art. A year later I started my third picture and I was re- 
markably surprised and delighted to see that in that short space of 
time you gentlemen had revolutionized the whole art, we could go 
anywhere we wanted to, we could say what we wanted to, our charac- 
ters could talk with their backs to the camera or move, and I certainly 
congratulate you gentlemen on having in that space of time adapted 
a very difficult and intricate science to the needs of this art. 

We tried to help as best we could in the Academy through our 
special committee, the Producers Technicians Committee under the 
chairmanship of Mr. Irving Thalberg, which has tried to coordinate 
the work of the various studios as far as it applied to the whole. Mr. 
Thalberg couldn't be here with you tonight but I have pleasure in 
introducing to you another member of the Producers Technicians 
Committee who will speak to you for a moment, Mr. Mike Levy of 
Paramount. 

W. 
250 



THE BANQUET 251 

Gentlemen: 

There is very little I can say about the Producers Technicians 
Committee because Mr. Thalberg is going to cover that in a de- 
tailed report which I believe one of the engineers is going to read as 
a sort of impromptu speech. I am pretty sure that Mr. Thalberg's 
report or rather the Report of the Committee is going to be very 
enlightening to even you engineers. When Mr. DeMille tells you 
that a great advance has been made in the art of talking pictures he is 
stating an absolute fact but it is my opinion that you have just 
started. There is a great deal more to be accomplished and I am 
sure that if the same progress that has been made in the last year 
and a half can be accomplished in the next year and a half, we will 
have so much greater latitude than we enjoy today that Mr. DeMille 
won't even have to come to the studio to direct his pictures. 

M. LEVY 

Members of the Society of Motion Picture Engineers: 

A little girl in school was once asked to give her definition of "man." 
The definition that she wrote down ran as follows: "Man is what 
woman has to marry ; he drinks, smokes, and swears and woman has 
to pick up after him. Both sprang from apes but woman sprang the 
furthest." 

I sometimes have a sneaking suspicion that it was woman who really 
invented speech. I feel quite sure that it was Mr. Edison's wife who 
instigated Mr. Edison to invent the phonograph and I am not at all 
certain that it isn't the wives of you engineers who have forced upon 
us the talking picture. However that may be, Mr. Watson, the well 
known psychologist whose behaviorism has become very popular, 
has made it a point in his psychology to express the idea that thought 
is really incipient speech ^reaction. Whether that is true or not, 
speech is certainly one of the most important forms of reaction which 
human beings indulge in woman perhaps more than man. 

For a long time the screen suffered from the great handicap of not 
being able to project speech. Fortunately for us actors, for the 
directors, and for the public at large, more especially for the writers, 
you have given us a means of projecting speech along with the photo- 
graphic images on the film. We, as actors, have had to learn a new 
technic but we have found that in learning that technic our art has 
been enlarged and enhanced in innumerable ways. The dramas of 



252 THE BANQUET [j. s. M. p. E. 

Shakespeare and the plays of Bernard Shaw would mean very little 
as silent dramas. You have given us, to my mind, what the screen 
never had before. It always had the dimensions of space and time; 
you have given it a brand new dimension, that of speech, and along 
with Mr. DeMille we heartily congratulate you and thank you for 

your gift to our industry. Thank you. 

MILTON SILLS 

Hello, Everybody! 

I am glad to be here and to wish you on behalf of Paramount a 
happy and successful convention. I think that you engineers who 
are responsible for giving to us this wonderful equipment for record- 
ing the voice as well as the action of the players deserve the thanks of 
the entire motion picture industry and have required a more exacting 
attention on our part. However, the results are worth the effort. 

Good luck. Thank you. - 

JUNE COLLYER 

Gentlemen: 

I consider it quite an honor to be given the privilege of addressing 
you all, although I am not at the dinner. I don't know whether you 
know what a great part you have played in my career, such as it has 
been or is going to be, because wherever I went, when I wanted to go 
in pictures they'd say "Nope, you haven't got a picture face." I 
used to look at myself in the mirror and I used to like me and I 
think I'm all right but they said "No, no picture face." and then 
you came along with this talking device and now I get along fine, 
very good in pictures I think, and I wish to thank you very very much 
for the most important part you have played in my career. 

H. GREENE 

Mr. Chairman, Ladies, and Gentlemen: 

This is an unexpected pleasure. I must necessarily make my 
speech entirely extemporaneous ; I had no chance to prepare anything 
at all. 

I find that everything I was going to say in compliment to your 
advance in the past year has been very capably and ably said by Mr. 
DeMille. I want to bring best wishes for a happy convention from 
Universal, from Mr. Carl lyaemmle, from our staff, and from the 
actors. Thank you. GLENN TRYON 



Aug., 1930] THE BANQUET 253 

Good evening, everybody! Now I wonder where my friend Mr. 
Merwin Palmer is. Oh there you are "Hello," and that goes for 
all of you. But really I do want to wish you, on behalf of Metro- 
Goldwyn-Mayer and myself, a very, very successful convention. 

Thank you. 

ANITA PAGE 

I am very glad to be here tonight and be able to wish you great suc- 
cess with your convention and thank you and congratulate you on 
your achievements in the past two years. Coming from the stage, I 
find pictures most interesting and quite different in a number of 
ways. I found the very first week I was here, that whereas on the 
stage you could go over in a corner and have quite a confidential 
chat about anyone and most anything you desired and no one ex- 
cept the pei son you were talking to would hear on Metro-Gold- 
wyn-Mayer sound stages not a chance. Anyway, the very best of 

luck to you. Good night. 

D. JORDAN 

I have been sitting off side here listening to everyone compliment 
you and tell you what a bunch of smart men you are, how clever, 
intelligent, and brainy you are but 1 don't think you are so hot. In 
fact, as long as you are so brilliant why don't you think of a way in 
which you can use old safety razor blades? 

But, inasmuch as I hadn't intended saying that when I came out, 
I would like to say that I think vou boys have done marvelously and 
my little part toward complimenting you seems very inadequate in 
view of the fact that Mr. DeMille, Mr. Sills, Mr. Green, and Mr. 
Tryon have all made remarkable speeches and I am quite sure any- 
thing I could say wouldn't be up to snuff. _ . 

B. NUGENT 

We have been indebted to the Fox Studios for recording our part 
of this entertainment. We are very grateful to them in the name of 
the Academy and now I want to introduce to you one of your own 
boys and if you send many more out here like him we'll be that much 
better pleased. Mr. Peter Mole of your own body. 

W. DEMiLLE 

Mr. DeMille on behalf of the Society of Motion Picture Engineers 
I want to thank the Academy and you personally and the members of 



254 THE BANQUET [j. s. M. P. E. 

your organization for arranging this splendid feature for our program. 
Fellow Members: 

We had the great pleasure in 1928 of having the convention here in 
Hollywood and I hope in the very near future you will decide to come 
to Hollywood again. I thank you. 

PETER MOLE 

It is a pleasure to extend a word of greeting to members and guests 
of the Society of Motion Picture Engineers. During the last few years 
the industry has been employing more mechanical, electrical, chemi- 
cal, and optical equipment in the production and exhibition of pic- 
tures with the result that engineering and the engineer have become 
of greater importance to the industry. In providing a common meet- 
ing place for the various engineering interests associated with the 
motion picture business your Society is fulfilling a need and the in- 
dustry is indebted to you individually and collectively for your con- 
tribution to the motion picture art. 

Warner Bros, welcome this opportunity to express their apprecia- 
tion of your part in the rapid development and growth of the industry 
and wish you success in your efforts to increase the pleasure and en- 
joyment of mankind by conquering and subduing the forces of nature. 
As I stand and think of what I first saw and the development that 
has taken place today, I can't help but think of what you will see in 
years to come and if you will look back, only then will you realize the 
great part which you have played to make this invention possible. 
Thank you. 

H. M. WARNER 

I am pleased to have the privilege of briefly greeting the Society of 
Motion Picture Engineers through the medium of this talking picture 
and I am sure you will be pleased in proportion to the brevity of 
the greeting. 

The General Theaters Equipment Company which, as you prob- 
ably know, I represent, has lately expanded its activities into the 
theater field itself. This company has always stood squarely for your 
motto of better pictures, that all-embracing term signifying better 
lighting, better projection, better screens, better sound, better every- 
thing pertaining to scientific and mechanical development of these 
arts. It may not, therefore, be construed as a mere nicety of expres- 
sion for me to say that our companies owe their existence primarily 



Aug., 1930] THE BANQUET 255 

to the accomplishment of the things for which this Society stands. 
Because of the particular branch of the motion picture business in 
which I have been most keenly interested for many years, I do not 
think I exaggerate when I express my belief that the present enviable 
position of this industry among all industries is due entirely to the 
untiring efforts of its research and scientific men. The scientist, the 
manufacturer, the producer, and the exhibitor, balanced with good 
business methods have created an industry so large and so close to 
the every-day life of the American people that our obligation to them 
for greater service is ever increasing. I believe the future of this 
industry lies to a very large degree in the creative power of you 
gentlemen of this Society and whatever recommendations you may 
give us we shall be glad to receive, and whatever assistance we may 
give to you we shall unhesitatingly give. The big picture, the wide 
vision picture if you please, is rapidly progressing. Its orderly adop- 
tion with due regard to all interests, the minimum loss to the industry, 
and the maximum benefit to both the industry and the public will 
soon be brought about. I am just as strong an advocate of big pic- 
tures as I ever was of little pictures but I am also an earnest advocate 
of the peaceful and harmonious advent of the big picture into the 
industry. 

May I thank you for your past cooperation and conclude by saying 
that the interests which I represent earnestly hope that we shall have 
sufficient prestige for the future to make our contributions not merely 
expedient but of such a nature that the public may always be better 
served. We shall endeavor to make our contributions to your scien- 
tific developments a worthy tribute to you all. 

H. L. CLARKE 

I am happy to greet this gathering of motion picture engineers. It 
is a great privilege to be able to speak to you through the medium of 
this wonderful invention the talking film. During the past fifty 
years I have witnessed with the greatest interest and satisfaction the 
growth of the motion picture industry. Of recent years that industry 
has demanded to an increasing extent the application of scientific 
and technical knowledge and will be far more dependent upon the 
work of the engineer in the future than in the past. I hope that the 
Society of Motion Picture Engineers will continue to flourish and to 
serve the industry. 

GEORGE EASTMAN 



256 THE BANQUET [J. S. M. p. B. 

Mr. Chairman and Fellow Members: 

I have been invited by Mr. Crabtree to say a few words to you 
through Movietone, and although this request conies during a rush 
visit in New York, I could not pass up this opportunity to prepare 
these few words. 

In the progress that the motion picture industry has made there 
never has been a period so great and promising as the present. With 
your help our industry is being reborn, offering possibilities for the 
future that stagger the imagination. The motion picture went much 
further as a medium of expression than any one originally dreamed it 
could go. This has been so with other great inventions. It has 
exercised a world-wide influence both social and commercial and was 
the greatest medium for the exchange of ideas and ideals that the 
world ever saw. The talking picture, however, will prove more ef- 
fective and influential because speech has made living people out of 
legendary shadows. Within a single year the entire entertaining 
world has changed; the transmission from the silent motion picture 
to sound motion pictures of today has been accomplished and has 
brought a wealth of new entertainment and joys. Its further progesss 
will, to a great extent, depend upon the contributions of the technical 
branch of the industry in which you are so vitally concerned. Until 
the motion picture has the reality of life itself your task remains 
undone. This result will eventually be brought about through the 
coordination of movement, sound, color, and the third dimension on 
a wide screen. If we can judge by the past, we can feel with a certain 
degree of confidence that all of this will be accomplished. Color is 
here and recent developments indicate that greater perfection will 
eventually be achieved in this connection. The wide screen is not 
alone a positive accomplishment but has actually shown subjects and 
scenes to great advantage indicating the possibilities of this broad- 
ened scope. When we have the dimension of depth and blend the 
different developments into one whole we will have the perfected mo- 
tion picture that will surpass any other medium of expression in 
beauty and reality. Because of this new medium, the peoples of dif- 
ferent nations will be brought together more directly and become even 
more familiar with each other's literature, humanisms, and ideals. 
Who knows but that perhaps through this medium not alone a world- 
wide understanding but a world-wide language may eventually re- 

Sult? H. B. FRANKLIN 



Aug., 1930] THE BANQUET 257 

Members of the Society of Motion Picture Engineers and friends of 
the Motion Picture Industry, since this is the first time that I have 
appeared before you, it seems proper that in a spirit of frankness I 
should tell you that in fact I am an engineer. This is a fact which I 
have carefully tried to conceal from my associates in the telephone 
industry, because they hold the belief quite strongly that in order to 
sell an engineering service and an engineering idea to the motion 
picture industry, it is necessary that one should be a business 
man. If I can persuade you that I am either an engineer or a 
business man, then it follows that I am neither, I am in fact a sales- 
man. 

Someone has said that salesmen are born, not made. I am sure 
that this can't be true of engineers, because the good Lord in his 
wisdom in creating man in his own image would never have had 
in mind the creation of an engineer. So intimately is the work 
of the engineer and the business man interwoven in every mod- 
ern business undertaking that no engineer can be successful in 
his calling unless he has about him something of the business man, 
and in turn no business man can be successful unless he is somewhat 
of an engineer. 

The engineer in the motion picture industry has come into his own 
largely since the introduction of sound, and it is the introduction of 
sound that has given us our opportunity for making to the motion 
picture industry an engineering contribution which is the foundation 
of the success of so many business enterprises today of national scope 
and importance, and I want to congratulate you upon the work which 
you have done in the past, but more particularly upon the opportuni- 
ties which lie ahead of you in the future for performing that service 
which is characteristic of the engineer. If it is important that the 
engineer and the business man should work shoulder to shoulder, how 
much more important is it that we engineers should stand together 
and work in cooperation and in harmony; and I want to assure you 
on behalf of the American Telephone Company and its subsidiaries, 
the Western Electric Company, Electrical Research Products, and the 
Bell Laboratories, the largest engineering research organization in the 
world, that, it is our steadfast purpose, it will be our constant endeavor 
to work shoulder to shoulder with you for the progress of science, for 
the greater glory of the engineer, and for the greater prosperity of the 
motion picture industry. Thank you. 

JOHN E. OTTERSON 



258 THE BANQUET [J. S. M. P. E. 

It is a pleasure to greet fellow-craftsmen of the engineering profes- 
sion at this dinner of the Society of Motion Picture Engineers. To 
those who enjoy the difficult and often doubtful process of thinking 
their way into an ever-expanding world the influence of our modern 
technical sciences upon the progress of the arts must be an interesting 
subject indeed. Science has made man a versatile creature. Rela- 
tively speaking, man has poor eyesight yet invention has enabled him 
to peer into the remotest heavens; his sense of hearing is limited 
yet a mere whisper spoken into a microphone reaches him across the 
expanse of an ocean; he is heavily limbed yet he has developed 
modern transportation units that enable him to travel 300 miles per 
hour; he is a land animal, yet he can explore the bottom of the sea; 
he lacks wings, yet he can soar through the air with the speed of a 
bird. 

You of the laboratories and workshops of the motion picture in- 
dustry have the opportunity to re-create nature and man if not 
through substance, at least through shadows. The influence of 
modern electrical and technical development already is apparent on 
the motion picture screen. The future holds the promise of scenes 
reproduced with life-like fidelity in color, perspective, and stereo- 
scopic effect, of art forms that will include the opera, the stage, and 
the concert hall, and of the development of a medium that will be 
not only an instrument of entertainment but a great instrument of 
education and information as well. Thank you. 

DAVID SARNOFF 



SPEECHES PERSONALLY PRESENTED AND BROADCAST OVER THE 
COLUMBIA NETWORK OF THE NATIONAL BROADCASTING 

COMPANY 



Fellow Members, Guests, and Radio Listeners: 

On the occasion of the last birthday celebration of Mr. Edison, one 
of the questions asked him by the newspaper representatives was 
"What is the biggest thing the American people can accomplish dur- 
ing the next year and why?" and the grand old man said, "Pay more 
attention to engineers than to politicians." 

As you know, Mr. Edison played a very important part in the de- 
velopment of the motion picture industry and I venture to think that 
when he gave this answer he had particularly in mind the motion 



Aug., 1930] THE BANQUET 259 

picture engineer. As for the politicians, I am sure that he didn't 
have in mind the many representatives that it has been my pleasure 
to meet here in Washington who are emulating Mr. Hoover by their 
interest in technical matters. 

For the benefit of our radio friends, I want to explain the meaning 
of the letters, S. M. P. E. They mean the Society of Motion Picture 
Engineers, the word, "engineer," being used in its broadest sense as 
including everyone who contributes to the building of a motion pic- 
ture. We are united in fellowship because we realize that although 
when two men exchange dollars they have only one each, when they 
exchange ideas each one has two. 

The Society includes among its members some of the most able 
technicians and scientists of the age, whose researches have made the 
talking motion picture possible. I refer to such men as Eastman, who 
was the first to manufacture motion picture film commercially, 
Edison, who not only contributed to the early development of the 
motion picture projector but who made the pioneer experiments on 
recording sound on wax, Jenkins, who likewise has contributed 
many original mechanical devices to the industry and has assisted in 
the development of television, and Lee DeForest, who was largely 
responsible for the development of the vacuum tube which is the 
keystone of all sound recording and reproducing equipment. With 
this new tool DeForest, Hoxie, and others of the Research Laboratory 
of the General Electric Company at Schenectady, Case and Sponable 
at Auburn, and members of the Bell Telephone Laboratories, Inc., 
developed the modern technic of recording sound photographically on 
film. It is the efforts of our members such as Capstaff, Ives, Kelley, 
Mees, Troland, and others which have made the color motion picture 
possible. 

With this brief introduction it gives me great pleasure to present 
the master of ceremonies, the Honorable William P. Connery, Jr., 
Representative of the Seventh District of Massachusetts. 

J. I. CRABTREE, President 



260 C. FRANCIS JENKINS [j. s. M. p. E. 

THE ENGINEER AND HIS TOOLS 
C. FRANCIS JENKINS 

We are here tonight for a recreational hour in a convention of the 
Society of Motion Picture Engineers, a group of specialists gathered 
together with a basic thought, namely, to improve the tools of the 
profession. 

The line of our particular activities is picture entertainment, but all 
such conventions of engineers in every line have a like purpose, 
namely, to improve the facilities of their particular employment. 

Has it ever occurred to you that we act like civilized beings only 
because we have such a great and varied collection of tools such 
a collection of tools that we can live together in communities of com- 
mon interest? 

The tools available to us and our engineers are the things which 
enable us, we moderns, to live at all, although we usually think of 
them as means to decrease our labor and increase our leisure. 

As a definition I refer to "tools" as any physical aid to an end; and 
any clever applicator as an engineer, whether he be of uncultured 
mind or of a trained intellect; but each is helpless without tools. 

Tools have been the most civilizing influence in all man's history. 
It has changed him from a selfish food robber to a sympathetic 
neighbor. 

I cannot agree with some of my evolution friends. The prepon- 
derance of evidence proves there has been no evolution of man, but 
only an evolution in his tools. 

The stone age man was as clever and ingenious as modern man. 
His earliest handicraft was as adaptable and symmetrical as that of 
today. 

The scope of his works, and the fineness of detail of the product 
has developed with the refinement and additions to his available 
tools. 

Man's first aids doubtless were devices employed to obtain food 
and clothing more easily than he could do with hands and teeth alone; 
to be followed by tools to improve his shelter and security. 

Later he began to impress his will on others, requiring them to use 
these tools to the master's advantage; and so slave labor became an 
established institution. Next he turned to his personal use the 
natural forces about him, i. e., "fire, water, earth, and air." 

The known works which early man performed with an abundance of 



Aug., 1930] THE BANQUET 261 

slave labor and more and more ingenious tool equipment are marvels 
to this very day. Nothing in modern times exceeds these early ex- 
amples in majesty, in beauty, or in symmetry. 

Scientists of the National Museum tell me that "the beautiful 
leaf-shaped flint blade has never been made by modern man;" 
and that "today's quarryman cannot even guess how his predecessors 
removed and set up the great monuments of the past." 

But eventually tools were so many and so varied that they could 
not be learned unaided in a single lifetime. So institutions were set 
up to teach the young the artifices available to make easier for him the 
getting of food, clothing, and shelter; for example, an alphabet; the 
three R's; the multiplication table; pi times the diameter; the 
hammer; the level; the transit; the telescope, etc. 

But eventually tools became so numerous and so varied that no one 
man could master them all, even with every possible instructional aid, 
so he must learn the tools of a single trade; and thus specialists be- 
came common. 

The modern machine age really began when America was settled by 
the white man, for from that date the evolution of machine tools has 
grown with unprecedented rapidity. 

Soon the perfect slave of man was the machine ; and as it developed 
into an aid a thousand times more efficient than the human slave, 
the human slave was liberated. 

Our food, our clothing, our shelter, our transportation, our com- 
munication, which make living together possible for us, are products 
of tools, tools, tools; the human hand only guides the tool. 

But man is the same man he has always been; he is of the same 
stature, he is no more clever, is no more ingenious today than was 
primitive man. All known evidence is to that effect, and no evidence 
to the contrary exists. 

Why, if his evolution had been in stature, comparable to the evolu- 
tion of his tools, he would today be taller than the mountains; or 
if his evolution had been in mental attainment, he would be a super- 
man indeed, even a super-god. 

There has been no evolution of man, but only an evolution of his 
tools; and this fact is irreputable proof that man is a spiritual being, 
sprung from a discrete gens, not an offshoot from some early animal 
plasm. His evolution of tools differentiates him from all other living 
creatures. 

And as tools accumulate, more tools are available with which to 



262 C. FRANCIS JENKINS [J. s. M. p. E. 

make more tools, a tool evolution which equips the inventor to evolve 
newer tools for the use of the engineer in his attainments of greater 
and greater feats. Tomorrow's tool equipment is inconceivable 
today, and what can be done therewith is impossible of prediction. 

With this infinite evolution of tools we have put more and more of 
nature's forces to work for us ; coal, oil, gas, water ; all of them sources 
of energy we can see and touch. 

Tomorrow we will put to work those sources of energy which could 
rather more properly be spoken of as the intangible forces of nature; 
"a double bit on the teeth of the lightning." 

And these new forces will be distributed over like intangible chan- 
nels. Long copper wires will not be so essential as today. And over 
these intangible channels power can then be delivered where wires 
cannot reach. 

In 1837 a wire was stretched from Washington to Baltimore over 
which enough energy was transmitted to operate a telegraph re- 
corder. But now a similarly stretched wire carries the power to 
drive heavy interurban railway trains between these cities, and with 
the swiftness of the wind. 

Comparably, today, over an intangible radio channel, we send 
aloft energy enough to operate a communication device aboard an 
airplane in flight. Tomorrow we will transmit over this same in- 
tangible channel enough power to drive the motors of the plane itself. 

The next age is the age of electronics, the age of intangible contacts 
of man with man, and over channels against which physical obstacles 
will have little effect. Energy to light, to heat, and to cool our houses, 
and for general communication, transportation, and control, may then 
be distributed without limits over the whole earth. 

As far as our picture engineers are interested, I confidently assert 
that the tools are now within sight when distant scenes and notable 
events may be reproduced in our homes and on the screens of our 
theaters simultaneously with their happening; and when motion 
pictures will be distributed from Hollywood directly by radio instead 
of by film. 

The Society of Motion Picture Engineers, in the fourteen years since 
its organization, has seen tremendous developments in this greatest 
of human entertainment, motion pictures; but the next fourteen 
years will see even more startling developments, and the audience 
many times multiplied, as radio is substituted for film as a carrier of 
this entertainment. 



Aug., 1930] THE BANQUET 263 

SCIENTIFIC PROGRESS AND THE NEW ERA IN MOTION PICTURES 

WILL H. HAYS 

We live amid infinite resources. Human ingenuity and human 
patience are the touchstones which discover those resources and 
transform them into tools for our progress, convenience, and pleasure. 

Addressing a gathering of engineers, research workers, and tech- 
nical experts, and discussing the tremendous impetus which scientific 
development has given to the motion picture, I shall presume to re- 
view these achievements only in the light of the greater promise which 
the new art brings weekly to 250,000,000 people a world multitude 
that finds recreation, inspiration, and satisfaction in the play of 
sound and sight now reflected by the screen. 

You, who have worked quietly in laboratories to develop the chemi- 
cal, mechanical, and electrical processes that have made motion pic- 
tures the world's first universal form of entertainment, need no stimu- 
lus from me. The future is the blazing goal that continues to beckon 
to you. Your contributions to motion picture development have 
followed each other in amazing succession. Writers, directors, and 
artists have had to tax their ingenuity to absorb and utilize the ex- 
panding powers and the new devices which you have put at their 
disposal. Producers have added a new and brilliant chapter to the 
history of industrial achievement, by their rapid and universal adop- 
tion of sound, your latest contribution. The financial fabric of our 
nation has responded to the stability and good management which 
the motion picture industry has achieved during the last decade and 
has put behind you and us the millions necessary for further research 
and for marketing the product you have made possible. The public 
has responded with an increased patronage of millions weekly to the 
appeal of the new art created by sound. 

Crossroads of Progress. A few years ago the motion picture indus- 
try stood at the crossroads of progress in picture development. An 
art had been created based on the pantomime of lights and shadows. 
Photography, apparently, had lavished its greatest resources on the 
screen. The progress of studio technic had made silence eloquent 
with action. The spectacles of ancient and modern history had been 
reconstructed for motion picture backgrounds. Talented men and 
women had developed a new artistry of acting for the screen. Writers 
and dramatists had learned to create special forms of entertainment 



264 Wiu, H. HAYS [J. S. M. p. K. 

based on the opportunities of the motion picture art. The fields of 
literature, history, and drama were combed for source material to 
inspire picture production. 

In a few years the industry had passed from the peep show to the 
motion picture palace, forging ahead with giant strides to create a 
new and ever-growing art for the world's democracy of entertainment. 
This was a great achievement indeed. 

But for those who take the helm of leadership there is no stopping 
on the road of scientific and technical progress. The word "stabiliza- 
tion" does not exist in the lexicons of science or of art. One scientific 
discovery either prepares for, or makes way for, another. A true 
art form is a living, growing thing. 

The Screen Finds a Voice. Sound came to the industry, and almost 
overnight the screen found a voice. Silence no longer stood in the 
way of film development. The motion picture screen, which had 
reflected through pantomime, life, literature, history, and the stage, 
found new reservoirs of material. The whole world of opera and 
music was opened to the movies. In a marvelously brief period new 
forms of entertainment were actually created that increased the 
motion picture audience of the United States last year by more than 
15,000,000 people weekly making the total weekly attendance 
115,000,000. 

The sound motion picture will become equally the servant, the 
universal servant, of education. I doubt whether even you, who have 
been fashioning the implements of the new magic, have had time fully 
to realize what you have done for the education of the world. The 
truth is that you have created the textbook of the future, a contribu- 
tion to the spread of greater knowledge unequalled since the Guten- 
berg Bible became exhibit "A" in the history of movable type. 

You heard on Monday from Mr. Tuttle of the special lights and 
camera processes which have been developed for the particular pur- 
pose of making colored motion pictures of great surgical operations. 

Progress of Medical Films. The medical profession has been 
splendid in seeing the possibilities of the motion picture as an imple- 
ment of instruction, and the important experiments which have been 
conducted at the Eastman laboratories are in response to a demand 
which grew out of conferences as early as 1926, when the industry let 
it be known to leaders in medicine and surgery that the wonders of 



Aug., 1930] THE BANQUET 265 

the motion picture were at their disposal. In that year the American 
College of Surgeons appointed a distinguished committee to develop 
the matter consisting of Squier, Chipman, Crile, Charles Mayo, 
Crowell, and Dr. Franklin H. Martin, now president of the College 
and a consistent leader in the entire movement. Mr. Eastman gen- 
erously supplied the funds, and the experimentation to lead to a cer- 
tainty of surgical films began. 

In those early conferences we were thinking in terms of the silent 
picture, unaided by the great corollary advantages of sound and color. 
Next September the College of Physicians at Columbia University 
will have ready a series of sound films for instruction and the medical 
schools of Johns Hopkins, the University of Pennsylvania, the Uni- 
versity of Michigan, and Ohio State are part of a group which expect 
to make and distribute these films. 

No longer will the country doctor be handicapped by his inability 
to travel to the medical education centers and take an unending series 
of post-graduate courses in a science which progresses steadily from 
year to year. He can see the newest in technic, vividly portrayed 
on tHe screen, with each movement of the skilled hand displayed and 
every reason for the method concurrently explained by the master 
who is performing the operation. 

Imagine the value of a close-up, slow motion picture in color of a 
Mayo, Crile, or Squier performing a difficult operation and describing 
it minutely, so that instead of 20 students watching from a balcony it 
could be shown to 100,000 students a score of times if necessary ! 

The Textbook of the Future. This great contribution to the advance- 
ment of surgical science is an impressing way but only one of the 
myriad ways in which the talking motion picture in colors will be- 
come the textbook of the future. In September of last year I wrote 
a letter to 573 university and college presidents, asking them to outline 
fields of activity and detail in which the motion picture might serve 
the cause of pedagogy. All replied, and more than 300 contributed 
useful and inspiring suggestions. These suggestions are being studied 
and will be applied. 

What would it add to the pageant of history, if Washington were 
to speak to us from his own time through the medium of the films? 
If, here, tonight you could see and hear Faraday discuss electricity, 
if Steinmetz through the living sound and motion of the screen could 
confront you tonight? If the nation, through a film broadcast, 



266 WILL H. HAYS [J. S. M. p. E. 

could hear Lincoln tonight? If, in addition to the facts gathered 
from books, we could feel the vibrant force of other famous person- 
alities of the past and the tempo of their age? 

These vast possibilities inherent in the audible motion picture will 
be your gift and the motion picture industry's gift to the future and 
these possibilities, I submit, challenge us all to make certain of the 
full use of their values. 

President Hoover Cooperates. Specifically, I desire to announce 
on this occasion that on behalf of the Motion Picture Producers and 
Distributors of America I have this day offered to the United States 
Government our aid in collecting and permanently preserving the 
picture records of historical events now available and which will here- 
after be made by the American motion picture industry. 

By this means the United States will take deserved leadership in 
the creation and development of the great library of the future. 
To the records of printed and written words which now comprise the 
pages of history, will be added the living records of sound, movement 
and color that will picture significant contemporary events to the com- 
ing generations with the vividness, realism, and certitude of life. 
The pageant of history, of education, of national events, and great 
local happenings will hereafter be recorded in the living tempo of the 
time in which the events occurred. 

This will be brought about by the joint action of our Government 
and of the motion picture industry. Committees will be appointed 
both by the President and by our industry to make this cooperation 
most effective. With the President this cooperation has been de- 
veloped and by him this afternoon I was authorized to make this 
announcement. 

In the vaults of our member companies are the negatives of all the 
principal contemporary historical events since the news weeklies 
made their record possible. Prints of these we will present to the 
Government to be preserved under its auspices in keeping with the 
best scientific practice. 

You of the Society of Motion Picture Engineers can aid the project 
with your technical cooperation, possibly by the appointment by 
your President of an appropriate committee of your organization. 
The best method of preservation you will develop. 

The Governmental storing facilities will be hastened, located in the 
place best suited for the purpose. In such building, also, may be 



Aug., 1930 THE BANQUET 267 

preserved the splendid war and other pictures taken by the Govern- 
ment agencies and now handled as effectively as is possible under the 
facilities available. 

Religion Profits from Films. I have had the pleasure, too, of plac- 
ing at the disposal of the International Motion Picture Institute at 
Rome the facilities of the industry to aid in cataloguing the world's 
present supply of educational films. That supply is only the alpha- 
bet of a literature, the spring freshet which will grow into a great 
river adding to the ocean of human knowledge. 

Culture, education, even religion are in heavy debt to you. Under 
the chairmanship of Dr. Howard LeSourd, of the Boston University 
School of Religious Education and Social Service, a committee of 
leaders in the field of religious education has just made public a study 
of the growing value of motion pictures to our churches and Sunday 
schools. They found that more than 2000 churches in the country 
now make some use of motion pictures in connection with services 
or teaching, and this number is growing every week. "The future is 
bright," the committee report says, adding, "The opinion of ministers 
experienced in the use of motion pictures as to their future possibilities 
for religious education in its broad sense is overwhelmingly positive. 
It seems to them that a mere beginning has been made and that the 
church should look forward to an ever-increasing and more efficient 
use of pictures in its program. There is every prospect of the church 
utilizing to the full this marvelous new art for the realization of its 
highest objectives." 

Entertainment a Vital Purpose. I need but add to the statement 
of these distinguished leaders in the religious field that the motion 
picture industry will continue to cooperate to the full in their high 
purpose. 

If I have stressed the great collateral values and services of motion 
pictures in education, in culture, in the broad aspects of religion- 
it is not because I underestimate for a moment the progress of the 
motion picture art in the field of wholesome entertainment. Enter- 
tainment itself is a vital purpose in modern life. It is a re-creating 
and rehabilitating influence that the world cannot do without. In 
the drab routine that covers the lives of so many millions of people, 
the entertainment picture comes to create a new will to do and a 
new viewpoint of life. It is not a luxury that pampers the eye and 
the ear ; it has become a necessity to the life of the world. 



268 Wiu, H. HAYS [J. s. M. P. E. 

It is inevitable, perhaps, that you of the Society of Motion Picture 
Engineers, who have fused many sciences to create these possibilities, 
should work largely unseen and unheard, in so far as the public is 
concerned. All the more the tribute of achievement is yours. 

Starting with the physical material on which the motion picture 
depends the film itself the research engineer has been the agent of 
the fundamental, essential progress. Next you have constantly im- 
proved the photographic eye which registers every scene and detail. 
The skill, thought, labor, and microscopically exact machinery re- 
quired to make camera equipment are in themselves miracles of high 
precision. The lighting problems presented by motion picture re- 
quirements have taxed the utmost resources of electrical science. 

Tribute to the Engineer. Through your accomplishments, the 
motion picture now walks and talks and acts and sings. 

To all this you are adding the tonal qualities of color, making great 
progress in translating nature in many of her glorious color effects. 
Your latest efforts are engaged in the problems involved in the per- 
fection of the wide-screen that would reproduce the scale and per- 
spective of life. 

Nor will you be satisfied with that; your vision is already sweeping 
toward three-dimensional effects or the illusion of stereoscopic re- 
production. That indeed would be life in motion on the screen. 

Through the technical developments which you have brought, we, 
who are entrusted also with the responsibilities of translating into 
performance the social and community factors involved in motion 
picture production, found more problems to solve. 

Sound brought a new army of authors, writers, dramatists, and 
artists and a vast field of new material to the motion picture studios, 
and the principles governing the maintenance of social and community 
values in the production of pictures had to be amplified, and new pro- 
visions added, in order that we might carry out our public respon- 
sibility. 

The Production Code recently announced on behalf of the motion 
picture industry crystallizes the production policies evolved by the in- 
dustry during the past eight years. It is a tribute to the vitality and 
importance of the motion picture art that few subjects have been so 
widely discussed. 

Nation Backs the Code. The public and editorial opinion which 
speaks for the fatherhood and motherhood of the nation, and which 



Aug., 1930] THE BANQUET 269 

* 

stands by the modern industrial dictum of public responsibility, has 
applauded the motives, the principles, and the aims which have led 
the motion picture industry of the United States to adopt such a Code. 
The overwhelming weight of opinion has been in this direction. 

The new Production Code is a challenge to the creative genius of 
all those who serve the art of the screen. It is a great step toward new 
artistic heights in motion picture production. It is a milestone in the 
progress of wholesome entertainment. The Code expresses the 
requirements of propriety, of good taste, and of public morals, in 
the production of motion pictures. It places no frontiers upon the 
progress of art. It restricts no man or woman with a worth-while 
message to deliver. It puts no bars upon the creation of wholesome 
entertainment. In banning vulgarity of scene or suggestion the 
motion picture industry is serving the public and serving itself. 
The virility of the art is not dependent upon vulgarity. 

No code, no regulation, no set of principles, is worth the paper it 
is written on unless there is a considered will and determination to 
observe it. The determination already expressed by producers, the 
enthusiastic support of picture directors, writers, and actors, the solid 
way in which the recent sentiment of the country is lined up behind 
the Code, will prove the strongest factors in its realization. We 
remember the necessity of a demand for good pictures as well as the 
necessity of a supply. Personally, I know the American public 
will support the best standards and I assure you that the supply 
of pictures so generally good now, will completely square with the 
promise of the Code when next fall or early winter the pictures made 
under this new and democractic instrument of self-regulation are 
released to the public. 

A Look into the Future. The future of the motion picture art is 
indeed brilliant in its promise of entertainment, cultural development, 
and of technical progress. Let us step for a moment into the cinema 
of tomorrow. It is a theater that surpasses the finest architectural 
achievement of the present, built solely for sound-picture entertain- 
ment. Magnificent orchestration, superb lighting, natural back- 
grounds of surpassing beauty prepare the eye and ear for what is to 
come. The curtain rises on a screen as wide as the theater's arch 
permits. Color and sound are blended in the brief prelude which 
sets the motif and tone for the evening. 

Music, composed for the film, in rising and falling tempo with the 



270 WILL H. HAYS [J. S. M. p. E. 

action, flows uninterruptedly during the performance, save when it 
dies away to permit the accentuation of voices. The photographic 
effects are no longer those of the flat screen; they have a marvelous 
illusion of third dimension, far transcending the stereoscope of 
childhood memories. 

To all this is added the final charm of color in Nature's true shades. 
Sunlight seems real sunlight, the tiniest variation of the shades of 
green in the leaves is there nature brought within doors. You hear 
the faint caress of the breeze on those leaves, the hum of insects, the 
twittering of birds, the light note of laughter of the boy and girl who 
start on the great adventure which is to be the film's story. 

You will deserve the first meed of praise for this miracle theater of 
the future, but there will also be praise due to the component parts 
of an industry that has with courage and patience absorbed every 
new invention and every refinement made possible by technical 
achievement. You have learned to trust the courage and willingness 
of the industry to go ahead; the industry, in turn, has learned to 
look with confidence to you for ever new and greater inventive prog- 
ress. To your work and to the work of those who make the pic- 
tures with the scientific wonders you provide, the American public 
and the world public has given an endorsement unparalleled in 
history. Such endorsement must keep us alert and alive to our great 
public responsibilities. 

REPLY TO MR. HAYS 

Mr. Hays I shall be glad to appoint a committee of the Society of 
Motion Picture Engineers to make recommendation on the best 
method of storing motion picture film records to insure their perpetua- 
tion. It is somewhat of a coincidence that a scientific paper giving 
the results of extensive research on this subject was presented at this 
convention by one of our members. 

Earlier in the evening we had the privilege of listening to speeches 
from well-known executives in the industry through the medium of 
our own invention the talking picture. We were addressed by H. L. 
Clarke, President of the Fox Film Corporation, George Eastman, 
Chairman of the Board of the Eastman Kodak Company, H. B. 
Franklin, President of the Fox West Coast Theaters, J. E. Otterson, 
President of the Electrical Research Products, Inc., D. Sarnoff, 
President of the Radio Corporation of America, and H. M. Warner, 
President of Warner Bros. Pictures, Inc. 



Aug., 1930] THE BANQUET 271 

We were also addressed by some of our fellow members on the 
Pacific Coast and by the president and other members of the Acad- 
emy of Motion Picture Arts and Sciences in Hollywood and after 
hearing all these eulogies, we realize more keenly than ever our future 
responsibilities. We shall continue in our efforts to improve the 
quality of sound reproduction and thereby add to the realism of the 
screen picture. We are fully aware that the theater patron is much 
more critical of sound quality than he is of the excellence of the photo- 
graphic image and the reason for this, I think, is that from the early 
ages we have been accustomed to accept the crudest drawings as 
representing the finished object. However, by no stroke of the 
imagination can you imagine that when I clap my hands the resulting 
sound is symbolic of an orchestra. Anything but a perfect facsimile 
of the sound we are endeavoring to reproduce is unsatisfactory to 
the ear. However, the ability of different persons to detect the finer 
points of musical appreciation varies greatly, but the public is rapidly 
becoming educated. We must keep ahead of this public apprecia- 
tion. The improvement in sound quality during the past six months 
has been remarkable and this only as a result of the concentrated ef- 
forts of the technicians in the research laboratories and studios, and 
the projection and acoustical engineers in the theaters. 

We realize that the scope for technical advance in the field of color 
motion pictures is almost unlimited. The definition or sharpness of 
the color motion picture must be improved and we must be able to 
render the colors of nature more truthfully. Also, many of the 
problems of the wide screen are as yet unsolved. Our Society has 
rendered a valuable service to the industry in preventing the pro- 
ducers from plunging blindly into this new development in the ab- 
sence of a suitable standard. The danger of the reoccurrence of the 
chaos which prevailed in the early history of the film business, when 
each producer used a different size of film, I believe, has been averted. 
Our Society is serving as a common meeting ground for the producers 
to agree upon a standard. 

The discrepancy of seeing shadows talk will eventually be over- 
come by the addition of depth to the picture. We are embarrassed 
by the optimism of the lay press with regard to an early solution of 
the problem of television. The public is becoming blase* and is sur- 
prised at nothing. The problem of televising so that the picture 
will be as large and as clear and rendered in color like the picture in 
the theater is an extremely complicated one and much more difficult 



272 J. I. CRABTRES [J. S. M. p. E. 

than that of reproducing sound. I feel that before our pictures are 
televised in color and relief some new fundamental scientific 
discovery will have to be made. Even then, the problem will only 
be solved by combined efforts on the part of many workers. 

There are two distinct kinds of research work: pure or fundamen- 
tal research, or the pursuit of knowledge for its own sake and with- 
out regard for its immediate value. For example, the vacuum tube is 
based on the electron theory of electricity a scientific discovery. 
There is also industrial research or the application to industry of 
principles discovered by pure research. There is a great need for 
more fundamental investigation and the incentive of profit is a safe 
guarantee that the new discovery will be applied. 

The industry needs a constant flow of new and vigorous blood into 
its veins and the logical fountain for this blood is the youth of the 
nation. To the ambitious sophomore who is technically inclined, I 
know of no better goal at which to aim than the motion picture in- 
dustry. This industry is unique in so far as it embraces more of 
the arts and sciences than any other industry with which I am ac- 
quainted so that a wide knowledge is necessary for success and the 
student should not attempt to specialize too much before leaving 
college. He should acquire as complete a knowledge as possible 
of optics, mechanics, electricity, mathematics, and some chemistry. 
This is said to be the age of specialization but no matter what scien- 
tific problem is tackled today it is necessary to draw upon knowledge 
from practically all the pure sciences. The successful scientist of 
today must be a "jack of all trades" and master of many of them. 

Up to within recent years the economics of the motion picture 
industry have been on an unstable foundation largely because of the 
lack of technical knowledge within the motion picture organizations 
but I predict that the successful motion picture executives of the 
future will be those having a technical or engineering training. 

In conclusion we, the members of the Society of Motion Picture 
Engineers, pledge ourselves to the advancement of motion picture 
engineering and the allied arts and sciences, thereby contributing to 
the increasing enjoyment of the motion picture patron upon which 
the success of this industry largely depends. 

J. I. CRABTREE, President 



Aug., 1930] MINUTES OF SECTIONS 273 

NEW YORK SECTION 

At a meeting held in the Engineering Societies Building on June 
12, 1930, Mr. L. M. Townsend, chairman of the Projection Com- 
mittee, presented the report of his committee in extenso. It will be 
recalled that owing to the crowded program at Washington it was 
unfortunately necessary to abridge the report of this committee 
but in view of its great importance the suggestion was made that 
the report be subsequently presented before the New York Section. 

An interesting discussion followed the presentation of the report 
which will be published in the next issue of the JOURNAL. 

Mr. S. K. Wolf of the Electrical Research Products Inc., also 
presented a paper entitled "Factors Governing the Size of Sound 
Reproducing Equipment in Theaters." 

The chairman announced that the next meeting will be held early 
in October and arrangements are being made for a visit to the 
Radio Victor Corporation, Camden, N. J. 

CHICAGO SECTION 

The second meeting of this section was held on June 19, 1930, at 
the Webster Hotel, Chicago, 111. A lengthy discussion regarding 
papers to be presented before the section took place and several 
papers were promised. 

Chairman Dubray announced the appointment of the following 
committees : 

Membership and Subscription 

Mr. Eugene J. Cour, Chairman Mr. M. W. La Rue 

Mr. E. A. Bertram 

Progress 

Mr. L. P. Langford, Chairman Mr. D. Tattenham 

Mr. R. H. Ray Mr. E. J. Cour 

The chairman announced that the next meeting will be held at 
the Adler Planetarium, Chicago. 



274 NEW CONSTITUTION AND BY-LAWS 

THE NEW CONSTITUTION AND BY-LAWS 

The amended constitution and by-laws were printed in the July 
issue of the JOURNAL. These contain a large number of amend- 
ments to the previous by-laws and attention is especially drawn to 
the following: 

(1) An applicant for Active membership must now be sponsored 
by three Active members instead of two as formerly. 

(2) A new class of membership, namely, "Sustaining members" 
has been instituted. 

(3) The new method of electing officers permits the entire 
Active membership to participate in the nomination of officers. 

(4) Commencing October 1, 1930, the initiation fees for both 
Active and Associate membership will become universal. During 
the past two years persons residing in territory other than the 
United States and Canada have enjoyed the privilege of half rate 
initiation fees, namely, $10 for Associate and $15 for Active mem- 
bership. On the date above mentioned a universal initiation fee 
of $20 for Associate and $30 for Active membership will be in effect. 

(5) Petitions for the formation of local sections must now be 
signed by 20 Active members instead of 10 as formerly. 

(6) Members become delinquent when their dues remain unpaid 
for 4 months. Two months after becoming delinquent, members 
will be dropped from the Society roll if non-payment is continued. 



j JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 
Volume XV SEPTEMBER, 1930 Number 3 



CONTENTS 

Page 
A Proposed New Series of Standard Focal Lengths for Motion 

Picture Projection Objectives WILBUR B. RAYTON 277 

The Becquerel Effect and Its Adaptation to Talking Picture 

Systems RUDOLPH MIEHLING 281 

The Storage of Valuable Motion Picture Film 

J. I. CRABTREE AND C. E. IVES 289 
Wide Film Shrinkage and Its Effects as a Factor in Determining 

Proper Dimensional Specifications for a New Standard 

A. S. HOWELL AND J. A. DUBRAY 306 
Considerations in the Design and Testing of Motion Picture 

Screens for Sound Picture Work H. F. HOPKINS 320 

Recent and Future Economic Changes in the Motion Picture 

Field FRANKLIN S. IRBY 332 

The Measurement of Density in Variable Density Sound Film. 

CLIFTON TUTTLE AND J. W. MC.FARLANE 345 
Sound-Proofing and Acoustic Treatment of RKO Stages. . . . 

A. S. RINGEL 352 

A Modified Film Waxing Machine 

J. I. CRABTREE AND C. E. IVES 370 

The Processing of Variable Density Sound Records 

R. F. NICHOLSON 374 

A Silhouette Studio C. FRANCIS JENKINS 381 

Abstracts 385 

Book Reviews 389 

Officers 390 

Committees 391 

Report for Consideration by the Committee on Local Sections 

of the Society of Motion Picture Engineers 394 

Society Notes 404 

Obituary 406 

New Members 407 

Unknown Addresses. . 410 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 

Associate Editors 

G. L. CHANIER P. MOLB S. E. SHBPPARD 

O. M. GLUNT W. B. RAYTON J. Z,. SPBNCB 

A. C. HARDY P. E. SABINE L. T. TROLAND 



Published monthly at Eastern, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
Editorial Office, 343 State St., Rochester, N. Y. 



Copyrighted, 1930, by the Society of Motion Picture Engineers 



Subscription to non-members $12.00 per year; single copies $1.50. Order from 
the Secretary of the Society of Motion Picture Engineers, 20th and Northampton 
Sts., Easton, Pa., or 2 Clearfield Ave., Bloomfield, N. J. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Application pending for second-class entry at the Post Office at Easton, Pa. 



A PROPOSED NEW SERIES OF STANDARD FOCAL LENGTHS 
FOR MOTION PICTURE PROJECTION OBJECTIVES 

WILBUR B. RAYTON* 

In the early days of motion pictures, projection objectives were 
supplied in a series of focal lengths which differed from each other 
by only an eighth of an inch. The burden of making and carrying 
in stock so great a variety of focal lengths became oppressive for 
both the manufacturer and the dealer and, in consequence, the 
Society at its Chicago meeting in 1917 1 adopted as standard a series 
of focal lengths in which the interval between numbers was a quarter 
of an inch. This practice has been followed up to the present day. 
The only further attention given by the Society to the subject 
of projection lens focal lengths consisted in adopting a standard 
permissible tolerance of plus or minus 1 per cent. 2 

At the present time the popular numbers include the range from 
4.0 in. to 8.0 in. in focal length. A variation of 0.25 in. in 4.0 in. 
amounts to 6.25 per cent; in an 8.0 in. focal length the same change 
is only half as great in per cent or 3.125 per cent. This range of 
focal lengths is required not so much because of any corresponding 
range in screen sizes as to accommodate a wide variation in pro- 
jection distance. A lens of 4.0 in. focal length will project a 20 ft. 
picture at a distance of about 90 ft. If a change is desired it must 
be to either a 3.75 or a 4.25 in. lens if we take the shortest available 
interval on either side. The corresponding change in screen size 
will be about 1.25 ft. If the projection distance is 180 ft. it will 
require an 8.0 in. lens to give the same size picture and the nearest 
focal length on either side will permit a variation of picture size 
of about 0.6 ft. The question arises as to why a minimum variation 

* Scientific Bureau, Bausch & Lomb Optical Company, Rochester, New York. 
(Read before the Society at Washington.) 

1 "Report by the Committee on Optics," Trans. Soc. Mot. Pict. Eng., No. 4 
(1917). 

2 "Report of Committee on Standards, May, 1923," Trans. Soc. Mot. Pict. 
Eng., No. 16 (1923), p. 314. 

277 



278 WILBUR B. RAYTON [J. s. M. P. E. 

of picture size which is satisfactory when dealing with a 4.0 in. lens 
should not be satisfactory if a lens is required of double the focal 
length. In fact, why should the series of focal lengths be based on 
an arithmetical increment at all except for convenience in remember- 
ing what lenses are available? It would seem much more sensible 
to make the series of focal lengths a geometrical series in which each 
focal length differed from the one before it by a fixed ratio. 

Under any circumstances this suggestion would merit considera- 
tion, but at the present time a new complication is introduced by 
the deplorable state of affairs introduced by the talking pictures. 

It is difficult to imagine just how the solidly entrenched ranks 
of directors, cinematographers, and exhibitors ever permitted them- 
selves to be manipulated into the position in which they now are as 
a result of the manner in which the sound-on-film process was 
developed. The appropriation of that relatively small area on 
the film for the sound record has played havoc with photography 
and projection. From the projectionist's standpoint, the attempt 
to project from the complete sound-on-film picture requires a mov- 
able mask at the screen to hide the empty space otherwise plainly 
visible and makes the projected picture so nearly square as to be 
decidedly displeasing. If, on the other hand, a mask is employed 
in the aperture in the projector to restore the original ratio of height 
to width either a smaller picture results or a projection lens of shorter 
focal length must be used. If the latter expedient is adopted we 
can restore the picture size, to be sure, but the center of it no longer 
coincides with the center of the screen and the lens must be shifted 
in a direction perpendicular to its axis to restore the center of the 
picture to its desired place on the screen. This violates all good 
optical practice and is responsible for some pretty bad projection. 
Ignoring the troubles of the studio, it is easy to see that the sound-on- 
film process has not filled the life of the projectionist with joy and 
it is to some degree surprising he has not made a more effective 
protest. 

To add to his troubles, the careful projectionist who tries to find 
combinations of focal lengths which will give pictures of the same 
size from Vitaphone and Movietone or Photophone film finds that 
in only a few cases is it possible. His film apertures differ in a definite 
ratio but available focal lengths differ in an arithmetical progression. 
The difference in film apertures is 11 per cent and if projection 
lenses could always be found which differ in focal length by just this 



Sept., 1930] 



STANDARD FOCAL LENGTHS 



279 



amount he could always project pictures of at least the same 
size. 

A series of focal lengths in which the interval was as great as 11 
per cent would be totally unsatisfactory because of too great change 
in picture size in passing from one lens to the next. Architects 
and exhibitors would undoubtedly raise violent protest. Two other 
possibilities exist, however, which should be considered. 

TABLE I 
Proposed Series of Focal Lengths, Interval 5.5 Per Cent 



3. 00 in. 


4.46 in. 


6.62 in. 


3.17 in. 


4.72 in. 


7.01 in. 


3.36 in. 


4. 99 in. 


7.42 in. 


3.55 in. 


5. 28 in. 


7.85 in. 


3.76 in. 


5 . 59 in. 


8.31 in. 


3.98 in. 


5.92 in. 




4.21 in. 


6.26 in. 





The first is to make the series of focal lengths differ by half of the 
11 per cent, or 5.5 per cent. This leads to the series shown in Table I 
wherein each focal length is 5.5 per cent shorter than the next longer. 
The constant difference of 5.5 per cent is matched in the present 
series at the lens of 4.5 in. focal length with a 0.25 in. interval be- 
tween it and the next number. It would correspond to a change of 
picture size of about 1.1 ft. in a 20 ft. picture. It leads to a series 
containing nineteen numbers between 3.00 in. and 8.31 in., inclusive, 
and seems to the writer adequate. 

TABLE II 

Proposed Series of Focal Lengths, Interval 4 Per Cent 



3. 00 in. 


4. 25 in. 


6 . 00 in. 


3.12 in. 


4.41 in. 


6. 25 in. 


3. 23 in. 


4. 58 in. 


6 . 50 in. 


3.37 in. 


4.75 in. 


6.75 in. 


3.50 in. 


4. 95 in. 


7. 00 in. 


3. 63 in. 


5. 15 in. 


7. 30 in. 


3. 78 in. 


5.34 in. 


7. 58 in. 


3 . 3 in. 


5. 56 in. 


7. 86 in. 


4. 08 in. 


5. 79 in. 


8. 20 in. 



The second possibility consists in dividing the 11 per cent into 
three parts, making the constant difference one of about 4 per cent. 
This suggestion leads to the focal lengths set forth in Table II con- 



280 WILBUR B. RAYTON 

taining twenty-seven focal lengths between 3.00 in. and 8.20 in., 
inclusive. The minimum change in picture size computed on the 
basis of a 20 ft. picture would here amount to about 0.8 ft. 

The difference between the two is that the manufacturer would 
have to make and the dealer to stock nineteen numbers to cover 
the range in the one case and twenty-seven in the second case. 
Since the success of the manufacturer and dealer both is to some 
extent at least essential to the success of the motion picture industry 
it should not overlook the possibilities of economy offered by the first 
suggestion. For comparison it is to be noted that at the present 
time there are twenty-two numbers in the series from 3.00 to 8.25 
in. The first proposal involves only three fewer numbers. 

DISCUSSION 

MR. DUBRAY: What are the permissible variations in focal length? 

MR. RAYTON: The Society adopted at one time a variation of 1 per cent 
from the indicated focus as the maximum permissible tolerance with the pro- 
vision that if the lens is too long in focus it be marked plus and if too short 
it be marked minus. 

MR. TAYLOR: As one might wish to change from full aperture to reduced 
aperture, why is it not feasible to use a supplementary lens to increase the mag- 
nification in order to cover the original screen area? 

MR. RAYTON: This depends on the aperture of the illuminating system. If 
we are dealing with an illuminant making use of only a small part of the pro- 
jection lens it will produce passable results. The demand is, however, for more 
and more light. This will, I think, lead to a demand for projection lenses of 
greater aperture. With an illuminant that fills the full aperture of such lenses 
the use of supplementary lensss will causa a noticeable loss in definition. 



THE BECQUEREL EFFECT AND ITS ADAPTATION TO 
TALKING PICTURE SYSTEMS 

RUDOLPH MIEHLING* 

At the mention of photo-electric cells, the mind usually visualizes 
a glistening silver bulb that serves the magical purpose in sound 
projection heads of converting a varying light beam into electrical 
impulses that eventually reach the audience as intelligible sounds. 
This electrical eye finds in the flickering light beams from the celluloid 
ribbon, voice, music, a pistol shot, or the murmur of the sea. 
In visualizing this every-day magical device, we neglect to include 
other types of photo-electric cells that have in the distant past and 
may in the near future have an important bearing on the develop- 
ment of sound picture systems. 

Strictly speaking, the term "photo-electric cell" may be applied 
to any device in which an electrical effect is obtained when it is 
exposed to the action of light. Of later years, the term has been 
reserved almost exclusively for that type of photo-electric cell em- 
ploying the Hallwachs effect. This phenomena, named for its dis- 
coverer, is based on the property of the alkali metals and some of 
their compounds of emitting electrons when illuminated. 

The familiar photo-electric cell is then simply a glass bulb con- 
taining a hydride of an alkali metal, usually potassium, with a central 
anode. The light falling upon the cell controls the emission of 
electrons from the alkali metal coating on the interior, thus affecting 
the current flow through the cell. 

Since the electrons moving in a gas atmosphere of low pressure 
are the factors determining the current flow through the cell, it 
follows that this type of cell is lightning-fast in response. With the 
electrons being emitted by the sensitive coating in practically direct 
proportion to the intensity of illumination, the photo-electric cell 
quickly displaced the selenium cell in the development of sound 
reproducing methods. 

* Universal Sound System, Inc., Philadelphia, Pa. (Read before the Society 
at Washington.) 

281 



282 RUDOLPH MIEHLING [j. s. M. p. E. 

The selenium cell, now classed as a photo- conductive type of cell, 
was the hope of the earlier experimenters with sound systems. 
In this type of cell, the current change is obtained by the action of 
light in reducing the resistance of annealed selenium when made 
into thin films between metallic conductors. It was soon found 
that selenium cells possessed inertia and refused to respond to rapid 
changes in the intensity of the light falling on them. For that 
reason they have been considered of little value for sound-on-film 
reproduction in this country. Abroad, they have been used to a 
certain extent by employing some special construction. 

There is a third group of cells which operate on an entirely different 
principle and which are classified as photo- voltaic cells. In the 
two former groupings, photo-electric and photo-conductive, it will 
be remembered the light impulses controlled the flow of current 
from some exterior source through the medium of the light sensitive 
cells. In the photo- voltaic group the cell generates a current when 
exposed to light and requires no outside source of current. This 
is the Becquerel effect and the adaptation of this type of cell to 
sound picture systems will be covered by the rest of this paper. 

Generally speaking, a photo-voltaic cell consists of two electrodes 
immersed in an electrolyte which has no chemical action on either 
electrode while the cell is in the dark. There may be, however, a 
slight dark current due to impurities that are never entirely absent 
in commercial materials which introduce but slight error in opera- 
tion. Upon illuminating the cell, an electrical potential is generated 
between the electrodes. This may be due either to chemical re- 
action in the electrolyte, or a reaction of the compound on one of 
the electrodes or to both causes. The particular phenomenon is 
controlled by the materials selected for the electrodes and electrolyte. 

The particular cell to be considered here employs a homogenous 
film of cuprous oxide on a copper plate as the light-sensitive com- 
pound. The second electrode is pure metallic lead while the elec- 
trolyte is a one per cent solution of lead nitrate in distilled water. 
This type of cell is the result of the development work by Wein 

The construction of the cell as developed for talking picture 
systems is shown in Fig. 1. The container is machined from bakelite 
or other inert material and by means of a conducting support the 
oxidized copper plate, circular in shape and having an area of I 1 / 4 
square inches, is mounted in the center of the container. A ring of 
pure lead is mounted on the shoulder turned in the casing. This is 



Sept., 1930] 



THE BECQUEREL EFFECT 



283 



connected to the terminal on top of the case. A soft gasket to pre- 
vent leakage is placed over the lead ring and the glass front clamped 
into place by the clamping ring. The solution is poured into the 
cell through the filler plug shown in the bottom of the casing. 



CONTAINER -(NEUTRAL MATERIAL) 



LEAKAGE GASKET 



CUPOROUS OXIDE 




NITPATE 



FILLING PLUG 
PURE LEAD 

IQUID RETAINING 
GLASS 



FIG. 1. Diagram of liquid voltaic cell construction. 

The active electrode, being the oxidized copper plate would natu- 
rally call for some care in its preparation. A clean copper plate is 
heated to a temperature of 800 C., resulting in the formation of oxides 
on its surface. The black oxide known as cupric oxide (CuO) is of 



284 



RUDOLPH 



[J. S. M. P. E. 



no value and, since it is formed on the surface, it can be dissolved 
off by immersing the plate in dilute hydrochloric acid. The removal 
of the black oxide exposes the cuprous oxide (Cu 2 O) just beneath 
which possesses the light sensitive properties desired. 

The type of cell construction shown results in a sturdy device not 
subject to damage even with rough handling, the only breakable 
part being the glass window which is reasonably well protected by 
the clamping ring. The device is practically immune from danger 
of breakage always present when fragile glass bulbs are employed. 




-92 



FIG. 2. Voltaic cell characteristics as a function of frequency. 



The electrical characteristics of the cell indicate the possibility 
of its application to talking picture systems and will be discussed 
before details of its use for that purpose are given. Possibly of 
major importance is the fact that its light flux-current characteristic 
is linear. The output of the cell is approximately 20 micro-amperes 
per lumen which compares well with the average photo-electric cell 
now used. It is evident that no extensive changes need be made 
in amplifiers to adapt this cell to existing sound systems. 

The frequency response of the cell further indicates its suitability 
for sound reproduction. There is no indication of inherent chemical 



Sept., 1930] THE BECQUEREL EFFECT 285 

lag although a marked capacitive action is present in the cell. To 
obtain the frequency characteristic curve shown in Fig. 2, a cell 
was coupled to a three stage transformer coupled amplifier. The 
cell was coupled to the first stage by a transformer having a d.c. 
resistance of approximately 45 ohms. (See Fig. 3.) 

The output circuit of the amplifier consisted of a 171- A tube 
connected as a rectifier with a micro-ammeter connected in series 
with the tube and the secondary of the output transformer. This 
gave a reading proportional to the square of the output voltage. 

As a variable speed light source, an involute tooth gear was re- 
volved in front of a straight filament lamp. This gave an almost 
pure sine wave with no second harmonics and but about 5 per cent 

TRANSFORMER 



Celt 



1 
I 



Input to tube . 



.0/5 Henrys. 

350/w PCffes/stavce. 

FIG. 3. Coupling of cell as used in test. 

third harmonic. The output of the cell was then measured and the 
results plotted on the curve shown in Fig. 2. 

The drop in impedance of the cell with increase of frequency 
demonstrates nicely the presence of capacity between the sensitive 
copper oxide plate and the electrolyte. The value of the capacity 
was checked by employing the discharge through known resistance 
and galvanometer method and was found to be in the neighborhood 
of 1.5 /if- The exact value varies somewhat with different light 
intensities of the higher order but at intensities present in sound 
heads the above value is reasonably accurate. 

The photo- voltaic cell can be resolved into an analogous electrical 
network built up of resistances, capacity, pure voltaic batteries, and 
an alternating current generator whose current output at a given low 
light flux (0.2 lumen or less) is constant and independent of the 



286 RUDOLPH MIEHLING [j. s. M. P. E. 

resistance in series with it. Such a network, shown in Fig. 4, serves 
to indicate the relative positions of the electrical components making 
up the cell. 

The capacity in the cell occurs between the Cu 2 O plate and the 
electrolyte which have an ohmic resistance of 50 and 150 ohms, 
respectively. Due to voltaic action between the cuprous oxide 
and the electrolyte, a voltage of 0.2 is generated. 

A similar voltaic action between the cathode and the solution 
gives rise to a potential of 0.17 volt. These two sources give rise 
to a dark current in the cell. The a.c. generator is analogous to 
the effect of variation in intensity of light reaching the cell. 

The values of resistance given for the copper oxide and electrolyte 
were determined by means of an a.c. Wheats tone bridge. 

The theoretical frequency curve of the analogous circuit checks 

C^O Resistance 

15 Md y * / H>2ts -C^O To Electrolyte 

JfConsta/tt Current A.C. Generator 

\_J7Volts. -Current f 'arses directly 
/JO Ohm * s L ' oh * /7 " x - 




Ektrolyt/c Resistance. 
. // VoZt Ca thoJc to SoJvt/on. 

FIG. 4. The electrical circuit equivalent of the photo- 
voltaic cell used in test. 

with the frequency curve of the cell within the limits of accuracy of 
the experiments, which was about 5 per cent. 

With such evidence of the characteristics of the cells, it should 
not be surprising to find they work with a high degree of satisfaction 
in a standard type of sound head, only requiring such modification 
of the input coupling to permit the use of the cell at maximum effi- 
ciency. Such changes as are found necessary result in a simplifi- 
cation of the assembly, eliminating all need of external batteries 
and coupling resistors. The latter are replaced by a coupling 
transformer with a primary impedance equal to that of the cell and 
a secondary suitable for direct connection to the grid of the first 
tube of the head amplifier. 

The necessary connections are shown in Fig. 5 where 227 type 
tubes are employed. The elimination of coupling resistors removes 



Sept., 1930] 



THE BECQUEREL EFFECT 



287 



one source of trouble often evidenced as background noise. No 
other changes are necessary either in equipment or mode of opera- 
tion. Slightly different settings of the fader may be required and 
a slight readjustment of the master potentiometer to assure the fader 
control functioning over the proper portion of the volume range. 

In summation, it can be said that the photo- voltaic cell employing 
the Becquerel effect has the following characteristics that make 
possible its adaptation to talking picture projection: 

1. Its physical structure is such as to make it relatively in- 
expensive and immune to mechanical injury. 



VOLTAIC CELL 




FIG. 5. Head amplifier circuit. 



2. The elimination of external current sources and its low im- 
pedance coupling device likewise lead to greater simplicity. 

3. Its frequency characteristic is such that the cell will respond 
satisfactorily to all sound frequencies that can be recorded at the 
present stage of the art and at present film speeds. 

4. The cell can be readily connected into and used with any 
type of sound head without extensive or expensive changes. 

5. Since it requires no adjustment beyond being properly mounted 
in the sound head, it actually reduces the responsibilities placed 
on the busy projectionist and service engineer. 



288 RUDOIyPH MlEHUNG 

DISCUSSION 

MR. EDWARDS: How does this cell compare in size with those usually em- 
ployed? 

MR. MIEHLING: The size of this cell is about l l /2 inches by 1% inches. The 
size and shape do not make any difference as long as it is properly exposed to 
the light source. 

MR. TAYLOR: The high frequencies fall off rapidly. 

MR. MIEHLING: It is inherent in the cell to fall off at higher frequencies. 

MR. TAYLOR: Ground noise is largely a matter of higher frequencies. Is it 
true that the falling off at the high end is the cause? 

MR. MIEHLING: That is probably the truth. 

MR. KELLOGG: I understand Mr. Miehling to say that the current sensitivity 
was about the same as a photo-cell. If this is true, the total power output is 
less than that of the photo-cell since the same current in a low impedance circuit 
represents less power. 

MR. MIEHLING : That is correct. 

MR. SANDVIK: It is true that the ground noise of this type of cell is much 
less than that of the photo-electric cell. 

MR. TAYLOR: Of course it is possible to cut down the ground noise or the 
needle surface sound by shutting off the high frequencies making the sound, so 
that any claim for reduced ground noise for one surface or another should be 
made on the basis of quality response, because everybody knows how to make 
ground noise if they don't eliminate high frequency in musical notes. 

MR. SANDVIK: If you use an equalizing network which results in a uniform 
gain up to 10,000 cycles, this cell still has relatively much less noise than the 
photo-electric cell. 

MR. MAURER: I should like to ask Dr. Sandvik whether the type of ground 
noise to which he is referring is that heard when the film is at rest in the pro- 
jector or when it is running. 

MR. SANDVIK: The noise referred to is that due to the photo-cell and not to 
the surface noise of the film. 



THE STORAGE OF VALUABLE MOTION PICTURE FILM* 
J. I. CRABTREE AND C. E. IVES 

The accumulation of valuable original negatives and master 
positives by the Eastman Kodak Company and the Eastman Teach- 
ing Films, Inc., during recent years has necessitated the construction 
of a suitable depository for this film. 

To date, most film storage vaults have been designed merely with 
a view to protection of the surroundings in the event of a fire within 
the vault. 1 This paper gives an account of experiments made with 
various .storage cabinets which have been designed so as to afford 
more protection to individual rolls of valuable film without increasing 
the risk to surrounding property. 

CRITERIA FOR THE STORAGE OF VALUABLE FILM 

At the outset it was considered that in the case of a vault suitable 
for the storage of valuable film the following conditions should be 
fulfilled: 

(1) In addition to being immune to external fires, the vault 
should be so constructed that in the event of an internal fire only 
a minimum quantity of film would be destroyed, and that a mini- 
mum fire menace to the surroundings would be incurred. 

(2) Each roll of film should be contained in a separate compart- 
ment and insulated so that one roll could be burned completely 
without setting fire to anything else. Each roll should be accessible 
separately so that the others would not be unnecessarily disturbed 
during inspection. Also, the different compartments should be 
vented in such a way that gases, soot, etc., from one burning roll 
would not reach any other roll. 

(3) The film should be shielded from water coming from any 
source. The most probable sources of water would be: (a) an 
automatic sprinkler discharge during a fire, (b) accidental discharge 

* Communication No. 447 from the Kodak Research Laboratories. (Read 
before the Society at. Washington.) 

289 



290 J. I. CRABTREE) AND C. B. IVES [J. S. M. p. E. 

of a sprinkler, (c) ceiling or pipe leaks, and (d) water on floor from 
leaks, sprinklers, and similar sources. 

(4) The method of storage should insure that the film is not 
subject to mechanical injury. If wound on too small a core the 
film will be curled excessively while, if a large roll is stored on edge, 
the circular shape of the roll will be distorted. 

Negative film should be wound on as large a core as is practical 
and should rest on its flat side. It is common practice to make a 
separate roll of each scene of a negative, the small rolls being placed 
on their flat sides in large square cans. In this condition it is very 
convenient to locate scenes by examining the ends. Obviously 
greater freedom from curl is insured if the film is stored in larger rolls. 

It is customary to store motion picture positive film on metal 
reels placed on edge. For long time storage this is not desirable 
because ordinary iron reels are apt to rust and the rust particles 
offset onto the film on rewinding, unless the reels are made of fiber 
or other suitable non-rusting material. It is satisfactory to handle 
positive film in the same manner as negative film. 

(5) The film roll size should usually be limited to 1050 feet unless 
the smallest handling unit is larger. A larger roll would mean 
unnecessary loss in case of fire. The rolls should be wrapped in 
paper or preferably in a sealed envelope which would not deteriorate 
rapidly in contact with the film. The wrapped roll should be placed 
in a round container made preferably of fiber, wood, or other non- 
heat conducting material which will not be damaged by nitrogen 
oxides. The container should have a loosely fitting cover and should 
not warp. 

(6) The storage compartment should be capable of being built 
up in units as required. Bach unit should occupy a minimum of 
space and also have a minimum weight per unit weight of film. 
Easy accessibility by the users and close proximity to a supply 
of electricity, steam or hot water, and brine will determine the loca- 
tion. 

. (7) The vault should be capable of being cooled to a temperature 
of 40F. to 45F., which temperature is considered sufficiently low to 
prevent appreciable decomposition of the film base with time. 2 
A temperature of 32F. or less would be very much more difficult 
to maintain and would introduce complications as regards fire pro- 
tection and handling of the film. 

(8) The vault should preferably be as immune as possible to 



Sept., 1930] 



STORAGE OF MOTION PICTURE FILM 



291 



earthquakes, vandalism, or destruction in time of war, but in this 
respect protection can be insured by making duplicate copies and 
storing these in places widely separated geographically. 

STORAGE DEVICES INVESTIGATED 

(1) The approved type of storage vault for motion picture positive 
film consists of a fireproof room with open racks for supporting 
the rolls of film which stand on edge in separate cans, each containing 
1000 feet of film. 3 Ample sprinkler equipment precludes the burning 
of large quantities of film or the explosion of decomposition fumes, 




FIG. 1. Plain wood experimental cabinet (front view). 

but if one roll becomes ignited, a number of others near it usually 
are decomposed or burned. Also in the event of fire a large quantity 
of film is apt to be damaged by water. These conditions make this 
type of storage vault undesirable for valuable film. 

(2) Steel lockers with sprinkler heads fitted at the top are like- 
wise unsatisfactory because the surroundings are imperfectly pro- 
tected. 

(3) Cabinets are available on the market in which the rolls of 
film are contained in separate vented compartments insulated from 
each other and from the outside. These cabinets afford satisfactory 
protection but the film rolls are stored on edge. 



292 J. I. CRABTREE AND C. B. IVES [J. S. M. p. E. 

(4) The Geyer Film Laboratory 4 has designed and installed a 
series of cabinets made of wood or asbestos board on the principle 
of a sectional filing cabinet. The front ends of the drawers are 
covered by means of a large door and the rear ends open into a 
common flue which permits the escape of any combustion fumes. 
Bach film roll (1000 feet) is placed inside a wooden box fitted with a 
telescoping wooden cover. 

At the outset it was considered that a cabinet built on the Geyer 
principle would be most suitable for the purpose intended because 
this would not depend on the use of water which often causes more 




I 



FIG. 2. Plain wood experimental cabinet (back view). 

damage than the fire itself. When a roll of film once catches fire 
it is impossible to save it even if it is quenched in water because 
the convolutions are then apt to stick together. It was therefore 
considered preferable to allow the roll to burn up completely, providing 
the adjacent rolls are protected from the heat and fumes resulting 
from the film combustion. 

Nature of Storage Cabinets Tested. A number of experimental 
cabinets designed on the filing cabinet principle were tested by 
igniting bare rolls of nitrate film in one compartment while the 



&pt., 1930] 



STORAGE OF MOTION PICTURE FILM 



remainder contained film both in the bare condition and enclosed 
in metal cans. 

The first test cabinet of 3 / 4 inch pine consisted essentially of several 
shelves separated sufficiently to allow the cover of the film can to be 
raised, to permit the free escape of gases. The rear opening of each 
compartment was closed by a flap while the front was covered 




FIG. 3. Sheet metal covered wooden cabinet (front view). 

by a single large door which could be closed tightly against an as- 
bestos gasket (Figs. 1 and 2). 

The design of a second wooden cabinet tested was similar to the 
above but this was covered completely with sheet metal. A series 
of holes were drilled through the metal at the ends of the shelves 
and uprights to provide vents for distillation products from the 
heated wood. Fiber rails, l /$ inch high and V* inch wide, were fastened 
to each shelf so as to create an air space between the film and the 



294 



J. I. CRABTREE AND C. B. IVES 



[J. S. M. P. E. 



shelf (Figs. 3 and 4). The sheet metal awnings or guards fitted at 
the lower edge of each shelf at the rear of the cabinet served to 
deflect the flames from the burning film into the flue and prevent 
their access to the upper compartments. 

Fire tests with the above cabinets indicated that the sheet metal 
covered cabinet adequately protected all other rolls when one was 
ignited, while in the case of the plain wooden cabinet the wood 




FIG. 4. Sheet metal covered wooden cabinet (back view). 



ignited while the first roll was being consumed and the remaining 
rolls eventually caught fire. 

A fireproofing paint was applied to one of the plain wooden cabi- 
nets but this did not give any apparent protection from fire, the 
cabinet being completely consumed. 

In view of the great expense involved in covering the wood with 
sheet metal, a cheaper cabinet was constructed consisting of a plain 



Sept., 1930] 



STORAGE OF MOTION PICTURE 



295 



wooden cabinet fitted with sheet metal drawers as shown in Figs. 
5 and 6. The drawers were open only at the end toward the flue, 
thus eliminating the necessity for a gasket-tight drawer, while at 
the back the sheet metal drawers extended beyond the cabinet 
into the flue spaces and were closed individually by weighted sheet 
metal flaps. This type of cabinet proved satisfactory and it was 
possible for a roll of film in one compartment to be completely 
consumed by fire while the remaining rolls were unaffected by heat 




FIG. 5. Experimental cabinet with sheet metal drawers (front view) . 



or fumes although the woodwork abutting the rear flue was somewhat 
scorched. 

At this point it was decided to make further tests with a storage 
cabinet of practically useful size with the sheet metal drawer type 
of construction. Figs. 7 and 8 show the design of a cabinet which 
has a capacity of forty 1000 foot rolls of 35 mm. film. This cabinet 
was tested by causing three 1000 foot rolls of 35 mm. positive motion 
picture film contained in three drawers to decompose simultaneously 



296 J. I. CRABTREE AND C. E. IVES [j. s. M. p. E. 

by the application of heat. Each of these rolls was contained in a 
sheet iron film can and had at its center an electric heater made 
by winding wire around a regular 2 inch wooden film spool. De- 
composition was started by closing an electric circuit containing 
these heaters. The decomposition progressed without the need of 
applied heat after once being started. 

When these rolls had decomposed completely, other rolls of film 
which had been placed in drawers adjacent to those where decomposi- 
tion took place and at other points were examined. The protection 




FIG. 6. Experimental cabinet with sheet metal drawers (back view). 

afforded from heat and fumes was entirely satisfactory. Even 
cans in drawers adjacent to those where the heat was evolved were 
not sensibly warm when inspected within ten minutes after the fire. 
A further test was made by exploding a mixture of the decompo- 
sition gases and air in the sheet metal chamber at the back of the 
cabinet by the use of automobile spark plugs. On the first trial 
one side was blown off from the wooden cabinet because the wooden 
dowels used to fasten it in place did not secure it sufficiently well. 
Parts of the cabinet made from ordinary oak were burned in the fire 
which followed the explosion but other parts constructed of chemi- 



Sept., 1930] 



STORAGE OF MOTION PICTURE FIL,M 



297 



cally fireproofed oak did not flame or glow after the flame from the 
burning material was removed. A second cabinet constructed with 
bolts to hold the woodwork in place was tested in a similar manner 
by exploding the gases given off during the decomposition of three 
1000 foot rolls of motion picture film. In this case the cabinet held 
together although the sheet metal was bulged on the sides. Several 
rolls of film in drawers adjacent to those where decomposition took 





/vi 

/ G 


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^ 


CONTINUE 
THROUGH 


s 


B 


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I 

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-V 


FLUE FASTENED TO 
^CABINET WITH SCREWS. 
/ USING ASBESTOS GASKET 


s 

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FNON- SHATTERING GLASS^ALV IRON FLUE J 
R LEFT SIDE OF CABINET *^ Z GA - 
.AYOUT MAY REQUIRE. 





o 







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B 


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o 




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. Front and 


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nation of unit cabinet. 



place were unharmed. Some of the latter rolls were contained in 
fiber boxes and others in light weight tin plate containers. Inas- 
much as no appreciable amount of heat reached this point the in- 
sulating properties of the fiber box were of no advantage and it was 
concluded that cheap metal cans, such as used by film manufacturers 
as containers for raw film, would be satisfactory from this point of view. 



298 



J. I. CRABTREE AND C. E. IVES 

CONCLUSIONS FROM FIRE TESTS 



[J. S. M. P. E. 



The above tests indicated that: 

(1) Cabinet compartments can be insulated from each other 
by a 7 /g inch thickness of air-dried pine, but if the wood is not ren- 
dered fireproof it is ignited by the burning film and eventually the 
entire cabinet is consumed. 

(2) It is necessary to protect the wood from fire, either (a) 



'/Q ASBESTOS^ 



(/) aJ 
U. 

02 



2u. 
h . 



</) y 





SECTION A- A 



LL |- 14 -1 ^___^__^^ 


V 


c-crcr'-c^<^_C_C=> ^ -33 ^ ^ ^ 


< 


OUTSIDE 
TO 
OUTSIDE 
OF 
DRAWER 


7 


1 


-y 4 "SHEET ASBESTOS 
^#26 GA. GALV IROhi^^ 


r 


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1 


5^55_^_^12Sjj 


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FIG. 



DOOR RESTS AGAINST^' 
3fa METAL RIB 

SECTION B-B 

8. Sections of cabinet showing arrangement of 
drawer and shelves. 



by covering it with sheet metal completely or at least in all places 
exposed to flame during a fire, or (b) by treating the wood by impreg- 
nation with fire retarding chemicals so that it will not burn after it 
has been heated. 5 

(3) The fire retarding paint tested was found to give practically 



Sept., 1930] STORAGE OF MOTION PICTURE FILM 299 

no protection to the wood but it is possible that it would have given 
more protection if it had been allowed to dry and harden more 
thoroughly. A chemically fireproofed oak treated by the Batavia 
Woodworking Company, Batavia, New York, was found sufficiently 
fire resistant for the purpose. It is expected that fireproofing the 
wood by one of the methods recommended by the Forest Products 
Laboratory of the U. S. Dept. of Agriculture would likewise be 
satisfactory. 6 

(4) If the outside of the cabinets or the chamber where they 
are housed must be protected by regular water sprinklers, the film 
should be covered in such a way that the water cannot reach it. 
The sheet metal drawers described give adequate protection. 

(5) Free vent must be afforded to gases arising from decomposi- 
tion of the film as otherwise there is danger of the gas pressure 
increasing until the container bursts. A committee of the Royal 
Photographic Society of Great Britain 7 has recommended soldering 
the tin cans in which motion picture film is stored. This is an 
extremely dangerous procedure. 

CONSTRUCTIONAL DETAILS FOR A FILM STORAGE CABINET 

As a result of the above experiments, a cabinet of the following 
design for the storage of valuable motion picture positive or negative 
film was constructed. 

The cabinet consists of two vertical columns of wooden shelves 
which are open at the front, and extend at the back into a galvanized 
sheet iron flue connected with the outdoors by means of a metal 
pipe (Fig. 7). The film is placed in sheet metal drawers closed at 
one end which slide between the shelves on Y 4 inch fiber rails. The 
drawers (Fig. 8) are thus separated at the top and bottom from the 
shelving by a one-quarter inch air space but a wooden board separated 
from the metal by an asbestos pad is fitted on the front of each drawer 
and fits tightly into the front of the compartment. This prevents 
the escape of any more than a trace of fumes from the front end of 
the cabinet in the event of a fire. 

The drawers are fitted with a metal flap at the flue end which 
is held shut by gravity. This serves to prevent the access of flames 
and gaseous combustion products to the adjacent compartments 
in the event of a fire in one compartment. The open ends of the 
drawers can be observed through wire reenforced shatter-proof glass 
windows fitted at one side of the flue so as to insure that the flaps 



300 



J. I. CRABTREB AND C. E. 



[J. S. M. p. B. 




are closed at all times. The completed cabinets of this design are 
shown in Figs. 9 and 10. 

The cabinet has a 6 inch high base and is 7 feet 10 inches high. 
Each compartment for 1000 feet of 35 mm. motion picture film has 
the following inside dimensions: H 3 /4 inches wide by 3 1 /z in,ches 
high by 16 inches deep. The sheet metal drawer is Il 5 /s inches wide 
by 3Vs inches high by 16 inches deep. When the wooden front is 

pushed in flush with the front, the drawer 
extends about one inch beyond the shelf 
into the flue (see Fig. 8) . 

VAULT FOR CONTAINING THE STORAGE 
CABINETS 

A number of the storage cabinets de- 
scribed above and which would come under 
the classification of "cabinets" under sec- 
tion D, article 17, of the Regulations of the 
National Board of Underwriters were placed 
inside a suitable concrete vault in order to 
protect the cabinets in the event of an 
external fire, to protect the surroundings 
in the event of an internal fire, and to 
enable the cabinets to be maintained at a 
constant temperature. 

The exterior of a typical vault is shown 
in Fig. 11. The outside wall is of brick 
and concrete while cinder block walls were 
used for the vault partitions. The roof of 
the vault was constructed of gypsum which 
is fireproof and has satisfactory heat insu- 
lating properties. Constructional details 
of such a vault should conform with Regu- 
lations of the National Board of Under- 
writers as described in their publication referring to the production, 
storage, and handling of nitrocellulose motion picture film. 3 

The method of installing the cabinets is clearly shown in Fig. 10, 
while the vent pipes connected to each cabinet and protruding 
through the roof of the vault are shown in Fig. 11. The conical 
shaped cap fitted at the end of each of the curved vents serves to 
deflect any flames from the roof in the event of a fire within the 
vault, 




FIG. 9. Unit cabinet to 
contain 40,000 feet of film. 



Sept., 1930] 



STORAGE OF MOTION PICTURE FILM 



301 



The temperature of the vault is maintained at 45F. to 50F. 
by means of brine pipes and radiators thermostatically controlled 




FIG. 10. Photograph of cabinets installed in storage vault. 

and placed on the walls near the ceiling. An alternative method 
of cooling would be to circulate chilled air. 
Attached to the vault in Fig. 11 is shown a small receiving room. 



302 J. I. CRABTREE AND C. E. IVES [J. S. M. p. E. 

Both this room and the vault proper have adequate sprinkler pro- 
tection. 

CARE OF FILM PREVIOUS TO STORAGE 

Both negative and positive motion picture film should be given 
careful processing in the laboratory before placing in the storage 
vault. After fixing in the normal fixing bath it should be immersed 
again in a fresh hypo bath to insure thorough fixation. Washing 




FIG. 11. Exterior view of vault showing ventilators protruding through 

the roof. 

should be thorough, the time required depending on the method 
employed, although from 45 minutes to one hour with suitable 
agitation of the film and adequate renewal of the wash water is 
usually sufficient. 7 - 8 A final soak for 5 to 10 minutes in distilled 
water is also desirable. 

After drying thoroughly the film should be spooled on wooden 
cores (not on metal reels), wrapped in chemically pure black paper 
of the type used by photographic manufacturers for packing un- 



Sept., 1930] STORAGE OF MOTION PICTURE FILM 303 

exposed motion picture film, and placed in ordinary tin plate cans. 
The tin plate or other rust resistant metal container is satisfactory 
provided it is inspected frequently so as to permit replacement 
before the film and its wrappings become contaminated with the 
products of corrosion. 

The moisture content of the film to be stored should preferably 
be such that it is in equilibrium with an atmosphere of 70 per cent 
relative humidity at 75F. before storing. Under these conditions 
no serious trouble will be encountered as a result of condensation 
of drops of moisture from the air in the can when the temperature 
is reduced to 45F. If, for any reason, film must be cleaned before 
storing, only liquids which do not attack the film should be used. 9 

EXAMINATION OF FILM AT INTERVALS 

Before exposing a roll of the cooled film to room conditions it 
should be warmed to a temperature above the dew point of the at- 
mosphere so that moisture will not condense upon it when it is re- 
wound. Moisture condensed on the film as dew would otherwise 
cause sticking of the film convolutions. A suitable warming cabinet 
maintained at a temperature of 75F. to 80F. and containing dry 
air should be located conveniently near the film vault. 

It is desirable to inspect all film by rewinding at least once every 
two years and if any signs of deterioration are visible a duplicate 
should be made. 

METHOD OF KEEPING RECORDS 

It is assumed that all film placed in the vault for storage is suffi- 
ciently valuable to merit considerable care in accounting for it. 
The following procedure for keeping records has been adopted 
by the Eastman Kodak Company. 

Each cabinet drawer is numbered and the film accounted for 
by such drawer numbers. On receipt of the film the custodian 
makes out a storage ticket in quadruplicate. The first copy is 
filed in the head office which is remote from the vault; the second 
is filed in a safe within the vault; the third is given to the individual 
depositing the film; and the fourth is placed in the can of film. 
At the same time, a record is made in a bound book for reference in 
case of loss of the ticket records. 

In order to withdraw film from the vault a duly authorized person 
whose signature is on file with the custodian signs the withdrawal 



304 J. I. CRABTRBE AND C. K. IVES [j. s. M. P. H. 

requisition and the custodian then compares this with his record. 
If the signatures and descriptions check, he removes the record from 
his file and the film from the vault and the messenger or other person 
who takes the film signs for it in the space provided on the customer's 
record. The custodian then delivers the second and third copies of 
the record to the head office and these records are then stapled and 
filed by the owner's name in a "dead" file and retained as a per- 
manent record of the transaction. The fourth copy is delivered 
with the film as an identification to the customer. All copies are 
cancelled with a rubber stamp marked "withdrawn" and dated to 
prevent "dead" records being confused with "live" ones. 

SUMMARY 

A description is given of a method of storing valuable motion 
picture film. The film is maintained at a temperature of approxi- 
mately 50F. and is stored in 1000 foot rolls in wooden cabinets 
which contain forty rolls of film. Bach roll is contained in a sheet 
metal drawer, the rear end of which is closed by a hinged metal door 
which leads into a common flue. 

Tests have shown that in the event of the ignition of any roll 
of film it is improbable that any of the other rolls of film will be 
injured. 

REFERENCES 

1 BLAIR, G. A.: "Reducing the Fire Hazard in Film Exchanges," Trans. 
Soc. Mot. Pict. Eng., No. 11 (1920), p. 54. 

"Experiments on the Storage of Motion Picture Film," Eastman Kodak Co., 
Rochester, N. Y. 

"Proceedings of a Board of the Chemical Warfare Service Investigating Con- 
ditions Incident to the Disaster at the Cleveland Hospital Clinic," U. S. Govern- 
ment Printing Office, Washington, D. C. (1929). 

2 CRABTREK, J. I.: "Handling Motion Picture Film at High Temperatures," 
Trans. Soc. Mot. Pict. Eng., No. 19 (1924), p. 39. 

3 "Regulations of the National Board of Fire Underwriters Governing the 
Production, Storage, and Handling of Nitrocellulose Motion Picture Films," 
National Board of Fire Underwriters, 85 John Street, New York, N. Y. 

4 STRAUSS, P.: "Rational Film Storage," Phot. Ind., 24 (Feb. 22, 1926), p. 
215. 

6 GARRATT, G. : "Fireproof Wood," American Lumberman (May 14, 1927), 
p. 56; (May 21, 1927), p. 52. 

6 "The Fireproofing of Wood," U. S. Department of Agriculture, Forest 
Products Laboratory, Madison, Wis. Revision of November, 1920. 

7 "Report of the Committee of the Royal Photographic Society, London: 
The Preservation of Negatives and Prints," B. J., 74 (Nov. 11, 1927), p. 668. 



Sept., 1930 J STORAGE OF MOTION PICTURE FILM 305 

8 HICKMAN, K. C. D.: "Washing Motion Picture Film," Trans. Soc. Mot. 
Pict. Eng., No. 23 (1925), p. 62; also CRABTREE, J. I., AND Ross, J. F.: "A 
Method of Testing for the Presence of Sodium Thiosulfate in Motion Picture 
Films," /. Soc. Mot. Pict. Eng., 14 (April, 1930), p. 419. 

9 CRABTREE, J. I., AND CARLTON, H. C.: "Cleaning Liquids for Motion 
Picture Film," Trans. Soc. Mot. Pict. Eng., XI (1927), No. 30, p. 277. 

DISCUSSION 

MR. R. C. HUBBARD: This is certainly a departure from the present recom- 
mended practice, and I think it has many good points. The capacity of the 
vault will be greatly reduced by this method of storing, and the size of the vault 
doesn't conform to the standard of the National Board of Fire Underwriters, 
which is a maximum capacity of 750 cubic feet of vault. 

MR. BRAUN: I should like to ask Mr. Ives what the average useful life of 
positive film would be if stored under ordinary room temperatures. 

MR. IVES: Mr. Jenkins has a film which he says is thirty or more years old 
and which is usable now. It depends a great deal on the degree of usage and 
the temperature of keeping. Some films have been given excessive heat treat- 
ment and have broken down in a short time. 

MR. HUBBARD: As regards the life of the film under ordinary room tempera- 
ture conditions, the matter of the condition of the air affects that; at high hu- 
midity there is more rapid deterioration of the film. I presume that Mr. Ives 
will take care of humidity as well as refrigeration in this storage vault. If there 
is too much moisture and it is condensed by refrigeration, it would cause serious 
trouble. 

MR. IVES: The film is wrapped in paper in the cans, and there should be 
little change in the moisture content of the roll. It is not similar to the usual 
condition in a vault where the can is exposed to the free circulation of air. 

MR. BRAUN: What causes the film to become brittle? 

MR. IVES: Loss of moisture causes brittleness. Low relative humidity of 
the atmosphere produces this condition. 

PRESIDENT CRABTREE: In reply to Mr. Hubbard about the volume of the 
vault, I don't think the regulation mentioned applies to a vault containing 
cabinets. 

With regard to the life of film, this is determined by the shrinkage and the point 
at which decomposition has reached such a stage that the image is incapable of 
being reproduced. In our experience, the maximum shrinkage is about 
2 per cent under conditions existing in Rochester and it has always been possible 
to make satisfactory prints on a step printer from negatives which have shrunk 
to this extent. When film is stored at 50 F. in an atmosphere which approaches 
saturation the degree of shrinkage will be less than at 70 F. to 80 F. at an average 
humidity of 50 per cent so that it can be reasonably expected that it would always 
be possible to make satisfactory prints from negatives stored in the vault under 
consideration. 



WIDE FILM SHRINKAGE AND ITS EFFECTS AS A FACTOR 

IN DETERMINING PROPER DIMENSIONAL 

SPECIFICATIONS FOR A NEW STANDARD 

A. S. HOWELL AND J. A. DUBRAY* 

Mr. Roebuck, in 1918, 1 and Mr. J. G. Jones, in 1923, 2 presented 
to this Society papers in which the all-important matter of film 
sprocket design was discussed and formulas given which served as a 
basis for the calculation of the diameters of the film sprockets; 
the pitch, thickness, height, and shape of the sprocket teeth to permit 
the accommodation of a chosen range of film shrinkage. 

The investigation was conducted for film of the standard 35 mm. 
size and for the standard Bell & Howell perforation 0.073 by 
0.110 in. diameter, 0.08228 in. length of flat sharp corner, 0.1870 
in. pitch, and 1.109 in. transverse gauge. 

The ever-increasing demand for an increase in film width and the 
extensive experimental work already conducted in this direction 
apparently justify the presentation to this Society of a paper dis- 
cussing the application of Messrs. Roebuck's and Jones' findings and 
conclusions to what is commonly referred to as the "Wide Film 
Development," and some recommended modifications in the arrange- 
ment of sound track and picture area for the appropriate widths 
which apparently have gained popular favor for the future sound 
film standards. 

It is well known that motion picture film is subject to swelling 
during the "wet" laboratory processes and that it shrinks in both 
the longitudinal and the transverse directions during its drying. 

Shrinkage continues for a long period of time after the drying 
process is completed, until at the end of its useful life it reaches a 
maximum estimated at from 1.5 to perhaps 3 per cent longitudinally, 
with an increase of approximately 10 per cent transversely over that 
of the longitudinal shrinkage. 

The above figures are, of necessity, only approximate, since film 

* Bell and Howell Co., Chicago, 111. (Read before the Society at Washington.) 
306 



WIDE FILM SHRINKAGE 307 

shrinkage is dependent upon many factors, such as manipulation in 
processing, atmospheric conditions to which it is submitted, and use 
and abuse in its manipulations during the exchange service period. 
Renovation also contributed to accentuate shrinkage as well as lack 
of proper storage facilities and improper attention as to humidifica- 
tion during the period of its useful life. Experience has dictated 
and proved Mr. Jones' contention that in actual practice the range 
of longitudinal film shrinkage can be confined between a minimum 
of 0.13 per cent and a maximum of 2 per cent, assuming the 0.13 
per cent shrinkage to bring about the condition of perfect mesh and 
the range between 0.13 and 2 per cent to represent the zone of working 
conditions which can be considered as most favorable. 

In order to maintain the best running condition of theoretical 
pitch during the period of the film's greater usefulness, the 0.13 per 
cent shrinkage has been decided upon as representing the condition 
of true pitch. The 0.13 per cent shrinkage value represents the 
condition in which the film usually leaves the processing labora- 
tory. 

Practice has, however, proved that a longitudinal shrinkage of 
1.5 per cent can be considered as a maximum seldom surpassed at the 
end of the useful life of the film and therefore the discussion and 
illustrations of this paper will be confined within the limits of 0.13 
to 1.5 per cent, although sprockets discussed and illustrated are 
designed to accommodate film shrunk approximately up to 2.5 
per cent within the limited arc of contact length of 0.748 in. 

The first problem which confronts the engineer is the determina- 
tion of the size and pitch of the film perforation in relation to the arc 
of contact of the film with the periphery of the sprocket. 

There is little or no theoretical data available at this time upon 
which to base the calculation of perforation size or pitches, but 
practice and actual experimentation lead to the conclusion that a 
critical length of perforation for over-all width of the film, as well as a 
critical height of the perforation can be determined with a sufficient 
degree of accuracy. The length of the perforation will be treated 
later in this paper when discussing the transverse shrinkage character- 
istics. 

In regard to height of perforation, it is apparent that the greater 
the film bearing surface, i. e., the greater the number of perfora- 
tions for a given length of film, the smoother is the running of the film 
because of the lesser degree of adjustment, or slight backward and 



308 



A. S. HoWELIy AND J. A. DUBRAY [J. S. M. P. 



forward movement of the film, which may be caused by differences 
in pitch between film and sprocket. 

It is also apparent that the driving strength of the film will be 
affected proportionally to the increase in the number of perforations 
in a given film length, partly because of the greater number of bearing 
surfaces thus provided. 




Sept., 1930] WIDE FILM SHRINKAGE 309 

On the other hand, consideration must be given to the inevitable 
weakening of the film material, or support, between perforations and 
a critical point can be practically determined where this weakening 
becomes excessive and where the stress imposed upon the film 
results in its breaking at the corners of the perforation. 

The determination of the arc of contact of film and sprocket 
for a projection machine and other machines used for exhibition 
purposes is limited to a length such that it will permit the running 
of the film without tooth engagement and disengagement interference. 

Fig. 1 may now be considered. At A an intermittent sprocket 
is drawn so as to answer the requirement of a 72 degree arc of contact 
for a perforation pitch of 0.234 in. as practiced at the present writing 
for film of a width of 70 mm. For economy of space, the sprocket 
drawn shows the existing condition for shrinkage of both 0.13 and 
1.5 per cent. 

Following Mr. Jones' formulas 2 and establishing the number of 
sprocket teeth at 16 (the accepted practice for 35 mm. film), we 
find that the base diameter of the sprocket (formula 7) should be 
1.1842 in. 

The circular pitch of the sprocket should be (formula 10 trans- 
posed) 0.2337 in. 

The tooth thickness for a maximum shrinkage of 2.5 per cent 
(formula 29) should be 0.0556 in. 

Although Mr. Jones' formula calls for a tooth thickness of 0.0556 
in., this has been reduced to 0.050 in. as shown at D, Fig. 1, because 
in practice it is considered favorable to increase the latitude of film 
perforation clearance for a given length of the arc of contact and for 
a given maximum shrinkage 

A check on the above results as per formula 15 proves that the 
maximum shrinkage that can be accommodated by a sprocket of 
the above dimensional specifications is approximately 3 per cent 
which is close to the imposed requirements. 

All other factors remaining equal, it is, however, possible to 
increase the bearing surfaces with the object of improving the 
smoothness of running of the film and considerably relieving the 
stress to which it is subjected, by reducing the perforation pitch 
so that five sprocket teeth are included in the chosen arc of contact. 

If the perforation pitch is reduced from 0.234 to 0.1872 in. and 
the same calculations are carried out, it will be found that the sprocket 
dimension will be as shown at B t Fig. 1. 



310 A. S. HOWEU, AND J. A. DUBRAY [J. S. M. P. E. 

Base diameter of the sprocket 1 . 1842 in. 

Circular pitch of the sprocket 0. 1870 in. 

Tooth thickness for a maximum shrinkage of approxi- 
mately 2.5 per cent . 0500 in. 

The increase in the number of sprocket teeth and consequent 
reduction in perforation pitch, as compared with the condition 
illustrated at A, offers a greater number of film bearing surfaces 
and is, therefore, more closely corresponding to the ideal condition 
previously expressed, while the film portion between perforations 
is of sufficient width to withstand the stress imposed upon the film 
and therefore offers greater protection against breakage. 

The above expressed considerations and dimensions apply to an 
intermittent, as well as to a film feeding sprocket, both of which 
function as film driving elements. 

A different condition is met when a take-up or hold-back sprocket 
is considered. The function of these sprockets is inverse. They 
hold back the film instead of driving it and are therefore driven 
instead of acting as drivers. Since only one of the teeth comprised 
in the arc of contact (except for the exceptional case of perfect mesh) 
can drive or be driven (as the case may be) in engagement with the 
film perforation, and since the leaving tooth is in both cases the only 
one in contact with the perforation, it results that the side paying 
off film is under tension, while the side paying in is loose in contrast 
to an intermittent sprocket for which the opposite condition exists. 

The slightest interference of free engagement of the film perfora- 
tion with the entering tooth, which may be caused by the looseness 
of the film at this end, will cause the film to take a longer path and 
be immediately crowded out of mesh. 

It is evident that the remedy for this condition is that the hold- 
back sprocket teeth shall have a circular pitch slightly less than the 
pitch of the perforation of the maximum shrunk film. 

The reversal of the function of the driven sprocket, as compared 
with that of the driver, calls for a reversal of its ability of accommo- 
dation. This can be secured by so reducing the base diameter of the 
sprocket that it will bring in perfect mesh the film when in its 
condition of maximum shrinkage. In other words, for a driven 
sprocket, the circular pitch of its teeth must be identical with the 
pitch of the shrunken film. 

This condition is illustrated at A 1 and J5 1 , Fig. 1, where it is again 
shown that for the predetermined perforation pitch of 70 mm. 



Sept., 1930] WIDE FILM SHRINKAGE 311 

film, a 20 tooth take-up sprocket, B l t presents considerable advantage 
over the 16 teeth illustrated at^l 1 , though both can accommodate 
film shrunk within the accepted limits without danger of interference. 
The take-up sprocket dimension can therefore be established as 
follows: 

Base diameter of sprocket 1 . 1679 in. 

Circular pitch . 1844 in. 

Tooth thickness . 0500 in. 

The shape of the tooth to be within the involute curve generated on the 
base circle. 

It remains now to calculate the transversal dimensions of the 
sprocket and sprocket teeth. 

In reference to Fig. 1, it shall be assumed that the over-all width 
of the film is 70 mm. and that in consideration of the over-all width 
of picture record, sound record, spacings between them, and spacings 
between outer edges of perforation and edges of film, the transverse 
gauge from center to center of perforations is to be 2.426 in. for un- 
shrunk film. 

The width of the perforation is the first dimension which must be 
established. 

It is quite evident that with the present knowledge of film behavior 
in regard to its resistance to stress, the conclusions which may be 
arrived at are based more upon practical experience than upon 
academic principles. 

It may be opportune to mention here the advisability of under- 
taking a thorough scientific investigation in order to verify or contra- 
dict the theories advanced in this paper before definite conclusions 
are derived from them. 

From this investigation, which would of necessity be rather 
laborious, the exact width of the perforation could be scientifically 
and therefore accurately derived for the film width which may be 
chosen as standard. 

It is, however, quite within reason to consider: First, that 
it is advisable to secure film registration from the sound track side 
of the film surface. Second, that the width of the perforation must 
be calculated proportionally to the over-all width of the film so as 
to permit the accommodation of the shrunken film without reducing 
to a harmful extent the transverse width of the tooth, which engages 
the perforations at the side opposite to the sound record. Third, 



312 A. S. HOWEJLL AND J. A. DUBRAY [J. S. M. P. B 

that an excessive width of perforation would tend to dangerously 
weaken the film. 

The above considerations lead to the conclusion that a critical 
perforation width can be determined with sufficient accuracy to 
assure satisfactory film registration and shrinkage accommodation 
with a minimum of film wear. 

With reference to film registration, the shape of the perforation 
plays an extremely important part. In consideration of the fact 
that a change in film dimensional standards demands alteration 
and rebuilding of all machinery used by the motion picture industry 
an improvement in the shape of film perforation can be considered 
without fear of encountering too many difficulties in its applica- 
tion. 

Commercial reasons have imposed upon the industry the present 
practice of two different sizes and shapes of perforation, one known 
as the Bell & Howell Standard, for negative films; and the other 
as the rectangular, for positive films; the first having a height of 
0.073 in. and the second a height of 0.078 in. for an equal width 
of 0.1 10 in. 

Such reasons disappear with the creation of a new film standard 
width, and it seems reasonable to conclude that only one pitch size 
and shape of perforation should be determined for both negative 
and positive films. 

This question has been discussed in papers previously presented 
to this Society and it has been conceded that the rectangular shape 
of perforation, with rounded corners, is the one most adaptable 
and that it presents the greatest opportunity of accurate film regis- 
tration, especially inasmuch as film control can be established from 
the film perforation instead of from the film edge. This procedure 
compensates whatever possible errors may be encountered in the 
different processes of film manipulation, for it is possible to register 
the film entirely from the perforation in both transverse and longi- 
tudinal control. 

Film control from the perforation also materially reduces the 
width of the surface to be registered and, by nearing the ideal con- 
dition of perfect registration, reduces to a minimum the necessary 
allowances for shrinkage accommodation. 

At C in Fig. 1, the dimensions of 70 mm. unshrunk film are shown, 
as well as an enlarged view of the rectangular perforation and its 
dimensions as accepted in the present practice, 0.080 by 0.130 in. 



Sept., 1930] 



WIDE FILM SHRINKAGE 



313 



At C l and C 2 are shown the dimensions that are assumed by the 
70 mm. film for transverse shrinkage of 0.14 and 1.65 per cent. 

It is to be noted that this range of transverse shrinkage has been 
chosen to correspond with the 0.13 to 1.5 per cent accepted range for 
the longitudinal shrinkage since experimentation proves that trans- 
verse shrinkage is approximately 10 per cent higher than the longi- 
tudinal. 




314 A. S. HowELL AND J. A. DUBRAY [J. S. M. P. E. 

In consideration of the fact that film control should be secured 
at the sound track side of the film, the width of the left-hand sprocket 
tooth, shown at D, Fig. 1, has been determined so as to fill the perfora- 
tion at its maximum shrinkage within tolerances of 0.0005 in. at 
each side of the tooth. 

If the right-hand sprocket tooth is now considered (D 1 , Fig. 1) 
it is found that in order properly to accommodate an over-all shrink- 
age of 1.65 per cent, its over-all width shall be reduced to 0.08215 
m. bearing on the flat portion of the perforation face. 

Experience proves that for a sprocket tooth, the mission of which 
is merely to guide the film, this ratio of bearing surface is amply 
sufficient and does not impose upon the face of the perforation such 
stress as would result either in breakage or in excessive wear of the 
perforation itself. 

As a final consideration, the shape ot the teeth must be determined. 
Since the corners of the perforation are rounded in order that they 
may present greater resistance to stress, the base of the sprocket 
tooth should be designed to follow this curve under all shrinkage 
conditions. The sides of the teeth should be parallel for a suffi- 
cient height to accommodate amply a maximum thickness of the film 
and then should be relieved by an angle of 15 degrees, as shown 
in Fig. 1, atDandP 1 . 

We shall now rapidly consider the present practice in perforation 
dimension for a film of a width of 65 mm. 

Fig. 2 illustrates at A and B the dimensions derived from Mr. 
Jones' formulas for an intermittent and a take-up sprocket, respec- 
tively, for a perforation of a pitch of 0.187 in. and a height of 0.078 
in. 

Since the consideration expressed for the 70 mm. film applies to 
the shrinkage of the 65 mm., we shall only remark that the following 
dimensions permit the accommodation of a longitudinal shrinkage 
ranging from 0.13 to 2.5 per cent. 

Number of teeth 20 

Base diameter of intermittent sprocket 1 . 1829 in. 

Base diameter of take-up sprocket 1 . 1666 in. 

Circular pitch of intermittent sprocket 0. 1867 in. 

Circular pitch of take-up sprocket . 1837 in. 

Tooth thickness . 0500 in. 

There is, however, no analogy between the two film widths in 
regard to width of perforation, which for the examples illustrated 



Sept., 1930] WIDE FILM SHRINKAGE 315 

at C, Fig. 2, has been kept equal to the width of the perforation 
used in 35 mm. standard film. 

Following the assumptions previously expressed in regard to 
critical width of perforation and of the apparent necessity of in- 
creasing the surface of the perforation, which bears with the sprocket 
tooth proportionally to the increase in over-all width of the film, 
it seems logical to assume that the width of the perforation for 65 
mm. film could be advantageously increased. 

Furthermore, considering the advantages derived by controlling 
the film at the left-hand perforation, that is to say, at the sound 
track side of the film, it is found that in order to accommodate a 
transverse film shrinkage of 1.65 per cent for an over-all film width 
of 65 mm., the width of the right-hand sprocket tooth would be 
0.0656 in. and its flat face would therefore bear only on less than the 
37 per cent of the flat face of the perforation. 

In order to increase this bearing surface, it has been proposed 
to enlarge the perforation width at the right-hand side from 0.110 
to 0.135 in., which would permit an increase in the width of the right- 
hand sprocket tooth to 0.0902 in., as shown in the section D of 
Fig. 2 thereby securing a bearing surface somewhat greater than 
53 per cent of the width of the flat portion of the perforation. 

Such increase in perforation width would indeed apportion amply 
sufficient bearing surface, but the unsymmetrical condition thus 
created would have the disadvantage of weakening the film at one 
side only, thereby unbalancing its resistance to stress. Furthermore, 
in actual practice, it would necessitate the use of sprockets having 
narrow teeth on both sides in order to avoid the constant danger 
of mutilating the perforations in the event of accidental or desired 
reversal of the film on the sprocket. 

The foregoing considerations have been expressed taking into 
account only the film dimensions proper, irrespective of the nature 
of the photographic images impressed upon it. 

The experience acquired in the past two years of sound picture 
production and presentation has lead the way to some conclusions 
which not only permit the improvement of the present technic, but 
also foresee future developments. 

It is, for example, of major importance that the sound record 
portion of the film should be properly supported and its running 
should be controlled with a great degree of accuracy. 

The transverse control is secured by the size and shape of the 



316 A. S. HowKLi, AND J. A. DUBRAY [J, S. M. P. E. 

perforation nearest to it and by appropriate side tension while the 
smoothness of running is, as previously seen, insured by proper 
sprocket design. 

There remains the necessity of controlling the film position in the 
focal plane of the sound reproducing optical system. It is quite 
evident that a mechanical support of the sound portion of the film 
is most desirable and that this support, to be effective, must offer a 
bearing surface of a certain magnitude. It is also not less evident 
than the support of the picture area of wide film demands more 
consideration than the smaller area of the 35 mm. standard in 
practice today. 

The spacings between edges of film and perforations, between per- 
forations and sound, or perforations and picture record, and between 
sound and picture records, assume considerable importance, since 
it can be said that they play a triple role: 

First. They must afford, as previously stated, sufficient film 
support. 

Second. They must eliminate the possibility of encroachment of 
picture record on sound record, which may result from film shrink- 
age. 

Third. They must eliminate the possibility of interference due 
to development streaks which may be caused by the perforations 
during the processing of the film. 

Fig. 3 shows the dimensional specifications proposed for films 
of an over-all width of 70 and 65 mm. 

Starting from the control side of the film and following an imagi- 
nary transverse axis, we notice that the space between the film edge 
and perforation is 0.100 in. 

The width of the perforation is, as previously determined, 0.130 
in. It is suggested that the inner edge of this perforation be used as a 
marginal guide for transverse registration of the film. 

Beside the perforation, a spacing of 0.083 in. is provided to elimi- 
nate the encroachment of development markings upon the sound 
record or of any burring, and to prevent interference with the sound 
record of slight cracking of the perforation. 

The film portion from the edge to this spacing is actually supported 
at the aperture plate, a section of which is shown directly under the 
drawing of the film. 

Next, a light shield 0.020 in. wide is suggested, the mission of 
which is to avoid the possibility of light encroachments upon the 



Sept., 1930] 



WIDE FILM SHRINKAGE 



317 




318 A. S. HOWELL AND J. A. DUBRAY [J. S. M. P. E. 

sound record which might be caused by either a swaying transverse 
motion of the film or by excessive shrinkage. 

The sound record has a width of 0.210 in. This dimension has 
been determined by increasing the standardized width of the sound 
record for the 35 mm. film proportionally with the increase in over-all 
width of the film. 

It may be opportune to note here that the width of the sound 
record can easily be increased, if found necessary, by reducing the 
width of the spacing between sound and picture records. 

The aperture plate is relieved at its portion corresponding to 
the sound record to permit free running and eliminate possible 
accumulation of dirt and consequent scratches. 

After the sound record another light shield is provided 0.020 in. 
in width, followed by a spacing 0.125 in. wide, which primarily allows 
means of providing a sufficiently great supporting surface at the 
aperture plate for both sound and picture areas. The mission of 
this spacing is also to eliminate the possibility of encroachment 
of the picture area upon the sound track in case of maximum shrink- 
age of the film. The distance between the edge of the film and the 
second light shield is 0.563 in. 

Let us suppose the picture record to be adjacent to the light shield 
and the side registration to be controlled by the edge of the film. 
If a shrinkage of 3 per cent is assumed, the edge of the picture record 
would be brought 0.017 in. nearer the scanning slit or at such danger- 
ous proximity to it that a side motion 0.003 in. in magnitude or any 
shrinkage in excess of 3 per cent would cause serious interference 
in the reproduction of the sound record. 

Following the spacing is the picture area itself, the width of which 
is, for the 70 mm. film, 1.740 in. or 44.19 mm. for the camera, and 
1.627 in. or 41.33 mm. for the projector aperture. 

It will be noted that the height of the apertures for the same 
film is 0.926 in. or 23.52 mm. for the camera, and 0.8739 in. or 22.20 
mm. for the projector, which appears to be a very pleasing pro- 
portion especially if the corners of the projector aperture are rounded 
as suggested with a radius of 3.67 mm. The ratio between height 
and width of the aperture is 1.87. 

With reference to the 65 mm. film, the ratio between height and 
width of the projector aperture is altered from 1.87 to 1.65. 

After the picture record there are found, first, another spacing 
0.098 in. in width, then the perforation, 0.130 in. wide, and finally 



Sept., 1930] WIDE FILM SHRINKAGE 319 

a spacing of 0.100 in. between perforation and edge of film which 
provides an over-all surface 0.328 in. wide fully supported at the 
aperture plate. 

It may be opportune to remark that the bearing surface at this 
end of the film is reduced from 0.328 to 0.282 in. for a shrinkage of 
1.65 per cent. 

The three bearing surfaces created by providing the suggested 
spacings are in the estimation of the authors essential for films of 
the widths which have been considered. 

The spacings have been calculated to afford protection to both 
the picture and the sound record, as well as to afford the best possible 
mechanical control consistent with resistance to wear and stability. 

It will be most opportune at this time to mention that from the 
engineering standpoint, we always consider the 65 mm. dimension 
preferable to the 70 mm., inasmuch as it will offer some advantages 
both in the matter of optical possibilities and more favorable condi- 
tions for better mechanical control. 

Screen size proportions have been discussed at length, and al- 
though it is apparent that there is a strong current in favor of a 
proportion of two to one, we believe that serious consideration 
should be given to this matter and the decision taken should be 
dictated by both artistic and technical considerations, and that the 
matter of proper film support and control should be accounted for, 
due to their importance with consideration for the life of the film. 

At the bottom of the figures, two conventional sprockets and 
their tooth dimensions have been drawn, indicating the possibility 
of sprocket design, involving interchangeability of the 70 mm. or 
65 mm. wide film with film of the 35 mm. standard width. 

The considerations of which this paper has been made the subject 
are presented to this body with the object of bringing forth argu- 
ments based upon the practice and the theory of motion picture 
film control and with an earnest desire on the part of the authors 
to contribute to the establishment of wide film standards. 

REFERENCES 

1 ROEBUCK, A. C.: "Sprocket Teeth and Film Perforation and Their Relation 
to Better Projection," Trans. Soc. Mot. Pict. Eng., No. 7 (November, 1918), p. 63. 

2 JONES, J. G.: "Film Sprocket Design," Trans. Soc. Mot. Pict. Eng., No. 17, 
p. 55. 



CONSIDERATIONS IN THE DESIGN AND TESTING OF 
MOTION PICTURE SCREENS FOR SOUND PICTURE WORK 

H. F. HOPKINS* 

In the design and selection of a suitable screen for use in sound 
picture systems, it will generally be recognized that the problem 
may be treated under two general headings, namely, that relating 
to the optical properties and that relating to the acoustic properties. 

From the point of view of the optical requirements, the problem 
is varied, depending upon the illumination available at the screen, 
the reflection and diffusion effects taking place at the screen, and the 
general effect of these upon the audience. These problems have 
been under investigation ever since the advent of the moving picture 
and a considerable amount of valuable data has been collected. 
Two papers bearing on this problem have been presented before this 
Society, one by Messrs. L. A. Jones and M. F. Fillius 1 and the other 
by Messrs. L. A. Jones and C. Tuttle. 2 Other workers in this field 
have applied themselves to this problem over a considerable period 
of time but to the best of our knowledge have not published their 
results. In spite of the considerable amount of work done, the 
diversity of the problem and the ever-changing conditions in the 
theater leave much to be discussed and interpreted by workers of 
the future. 

The introduction of the sound picture is one of the changes in the 
theater that has resulted in a considerable change in the motion 
picture screen. In its pioneer stages, the so-called "sound picture" 
was utilized generally only as a means for providing synchronized 
musical accompaniment for the picture, although in some cases 
attendant sound effects were incorporated in the recording along 
with the music. The general idea at that time was to place the 
loud speakers so as to obtain as nearly as possible the impression that 
the music was being provided by an actual orchestra. In conse- 
quence, the loud speakers were ordinarily placed in the orchestra 

* Bell Telephone Laboratories, New York. (Read before the Society at 
Washington.) 
320 



DESIGN AND TESTING OF SCREENS 321 

pit and the effects thus obtained were generally considered adequate. 
The ultimate goal of the synchronized sound picture, however, was 
the association of realistic dialog with the picture, the possibilities 
of which were immediately recognized. With the development 
of the art to a point where the recording of associated dialog was 
successfully accomplished, it became apparent that a more suitable 
location for the loud speakers must be found. If realism is to be 
attained, the character on the screen must appear to be the sound 
source. A suggested method for approximating this illusion was 
to place the loud speakers on the stage alongside of the screen, but 
it would appear that a more desirable place would be immediately 
behind the picture. This, of course, imposes as a requirement a 
screen which will efficiently transmit acoustic power as well as one 
which is suitable as a light reflector. In the Bell Telephone Lab- 
oratories considerations of the problem of obtaining a suitable 
screen have been limited largely to studies of the acoustic effects 
produced by the screen when used in the manner suggested, and it is 
the purpose of this paper to discuss these effects. 

In regard to the acoustic properties of a screen interposed be- 
tween a sound source and an observer it is to be expected that sound 
may be transmitted in various ways. The screen may be made to 
vibrate as a diaphragm under the driving influence of the sound 
emanating from the source and as a result of this vibration produce 
new sound waves that ultimately reach the observer. As a second 
possible manner, the original sounds may be transmitted through air 
passages in the screen material. A third possibility would be by 
wave propagation in the screen material as a conducting medium. 
Because of certain practical limitations to the permissible thickness 
of a screen, however, and because ot the physical properties of the 
materials that might be used in its construction, the power so trans- 
mitted would be small in comparison with that transmitted by either 
of the other two methods, and therefore no further consideration 
need be given this effect. In the following discussion the sound 
transmitted will be considered to result from either of the first two 
methods or from a combination of the two. 

A sound picture screen as a vibrating diaphragm may be expected 
to set up sound waves differing from those of the source in a number 
of respects. From a knowledge of the permissible tension to which 
a screen may be stretched, and of the density of the material used, 
it would be expected that the natural frequency of the screen as a 



322 



H. F. HOPKINS 



[J. S. M. P. E. 



whole would be low. At this natural frequency, the screen may be 
an efficient transducer, but for higher frequencies where the mass 
reaction becomes large, the greater portion of the driving force 
would be consumed in accelerating the screen and but little would 
be available for moving the air load. This natural frequency, 
however, is ordinarily below the frequency band of interest in sound 
picture systems and therefore, over this band, the transmission 
efficiency would be greatest at the lowest frequency and would de- 
crease as the frequency increases. Furthermore, under the condi- 
tions in which we are interested, the screen is far from a simple 
vibrating system and, therefore, irregularities will occur in the 
transmission characteristic, although the magnitude of these irregu- 




FREQUENCY 
FIG. 1. Effect resulting from a screen which acts as a diaphragm. 



larities may be small in comparison with the total effect. Other 
considerations in connection with diaphragm action are the altera- 
tion of the sound field due to a difference between the directive 
effects of the sound source and of the screen, and the possibility of 
reduction in the loudness effect due to frictional dissipation. 

Fig. 1 shows the effect of a screen in which the transmitted sound 
power results largely from diaphragm action. The ordinates of the 
curve indicate the effect of the screen on the sound pressure at the 
position of an observer for various frequencies. It is evident that 
the transmission loss increases with increasing frequency due to 
the mass reaction effect. The irregularities discussed above are also 
apparent. 

In regard to the transmission of sound through the screen by means 



Sept., 1930] 



DESIGN AND TESTING OF SCREENS 



323 



of air passages in the material, a device of this nature if properly 
designed may be expected to provide rather satisfactory results. 
In such a device, several features are of importance. The aggregate 
area represented by the openings in the screen must be of such magni- 
tude as to provide a proper air load for the radiation of sound into 
the theater, if efficient transmission is to be obtained. Also since 
the volume of the air in the individual passages presents a mass 
reaction to the flow of sound energy, proper dimensioning of the 
holes is of great importance. The ratio of the length of the passages, 
represented by the thickness of the screen material, to the area of a 
single opening should be small. Furthermore, if this requirement 
is met, the absorption of sound in transit through the screen will be 
reduced to a minimum. 



o 

z 

z - 
o z 

o <^ 
LJ <n 









































>V- 




f\r^/\ 




^^^s 




, s 




























| 


























ON 


~^? 














































<ooo <\j ^ <o eo o CM ^ <o a 





FREQUENCY 

FIG. 2. Effect resulting from a screen which transmits sound freely through 

open areas. 

Fig. 2 shows the effect of a screen in which the sound power in 
the theater is largely the result of transmission through openings 
in the screen. In this particular case, the aggregate area of the 
passages is about 44 per cent of the screen area. It will be observed 
that this device offers practically no attenuation to the transmission 
of sound throughout the frequency range of interest and that the 
irregularities in the transmission characteristic have been reduced 
to a negligible magnitude, except at the lowest frequencies, where 
the results are perhaps less reliable. 

In regard to the above screen, it is not desirable from the optical 
standpoint to provide too great an area for the sound passages. 
The tendency has been therefore to provide rather small, widely 
spaced openings, as a result of which, sound transmission might 
be expected to take place by a combination of diaphragm action 
and air passage conduction. Such a screen might be expected to 



324 



H. F. HOPKINS 



[J. S. M. P. E. 



provide results intermediate between those of Figs. 1 and 2 in re- 
gard to both transmission efficiency and uniformity of response. 
Fig. 3 shows the transmission characteristic of a screen of this type. 
This screen is similar in design to that of Fig. 1, except for the sound 
passages. A comparison of the two curves (Fig. 1 and Fig. 3) 
shows that the efficiencies at a frequency of 100 cycles are approxi- 
mately equal. At a frequency of 2000 cycles, however, the first 
screen (Fig. 1) transmits only about 4 per cent of the total sound 
power, whereas the other screen (Fig. 3) transmits about 80 per cent. 
Evidently, the transmission indicated in Fig. 3 for frequencies above 
2000 cycles is due almost entirely to the effect of the sound passages. 
The drooping characteristic in this range must therefore be due to 
the mass reaction of the air in the passages rather than to that of 



10 



IO 




tfV 



i_ (O 

o^ 

u 



R 




\jv& 



'VV 



FREQUENCY 

FIG. 3. Effect of a screen which combines diaphragm action with free 

transmission. 



the diaphragm. In Fig. 3 the aggregate area of the openings is 
about 4 per cent of the total screen area and consists of circular 
holes about 0.040 in. in diameter. The screen thickness is 0.030 in. 
It would appear from these dimensions that the effective mass of 
the air in the sound passages would explain the drooping effect 
observed. Also the aggregate area of the openings is of such magni- 
tude as to reduce the efficiency at all frequencies. In this particular 
case it would appear desirable to increase the aggregate area of the 
openings and to decrease the effective mass of the air in the passages. 
The latter effect can be accomplished by using a thinner screen. 
Fig. 4 shows the transmission characteristic of a number of screens 
of various degrees of perfection as judged from an acoustic stand- 
point. Curve A, as in Fig. 1, is representative of a screen in which 



3ept, 1930] 



DESIGN AND TESTING OF SCREENS 



325 



no air passages are provided. Curve B, as in Fig. 3, is the trans- 
mission characteristic of a screen similar to that in A except that it 
has openings presenting an aggregate area of about 4 per cent of 




AGGREGATE AREA Of OPENINGS 
44% OF TOTAL SCREEN AREA 



/vu 



AGGREGATE AREA OF OPENINGS 
5t OF TOTAL SCREEN AREA 
AREA OF INDIVIDUAL OPEN- 
INGS .0013 SO IN. 
SCREEN THICKNESS .013 IN. 



-10 
O , 



AGGREGATE AWEA OF OPENINGS 
5t OF TOTAL SCREEN AREA 
AREA OF INDIVIDUAL OPEN- 
INGS .0013 SO. IN. 
SCREEN THICKNESS .030 .IN. 



AGGREGATE AREA OF OPENINGS 
4% OF TOTAL SCREEN AREA 
AREA OF INDIVIDUAL OPEN- 
INGS .0013 SO. IN. 
SCREEN THICKNESS .030 IN. 



TYPE OF SCREEN USED BEFORE 
ADVENT OF SOUND PICTURES 



FREQUENCY 

FIG. 4. Transmission characteristics of several types of screens. 



the total screen area. Curve C indicates the results obtained 
with a screen similar to that of B except that the aggregate area of 
the openings is increased 25 per cent. It would appear that the 
increase in the combined area of the holes increases the air load 



326 H. F. HOPKINS [J. S. M. P. E. 

sufficiently to give a noticeable improvement in efficiency throughout 
the whole frequency range although the droop at the higher fre- 
quencies, due to the air mass, is still in evidence. Curve D shows the 
transmission characteristic of a screen in which the size of the holes 
and the percentage of the open area are the same as in case C. 
In comparison with the other characteristics shown the improvement 
in this case has been effected by reducing the thickness of the screen 
and hence the mass reaction of the air in the holes. It will be noticed 
that the irregularities have also been reduced. Curve E is the 
same characteristic as shown in Fig. 2 and is given here only as a 
matter of comparison. The open area of the screen represented 
by this curve is about 44 per cent of the total area and the ratio 
of the length to the area of the air passages is considerably reduced 
in comparison with that for the screen represented in D. From 
the standpoint of acoustic transmission this screen would seem to be 
almost ideal. In view of the characteristics shown in D, however, 
it would appear that good acoustic effects may be obtained with 
screens in which the area of the openings is considerably less than 
44 per cent, thus increasing the possibilities of improved optical 
performance. 

Thus far the screens which have been discussed are devices in which 
the air passages, if present, are punched or otherwise purposely 
manufactured into the screen. A great many commercial screens 
are made of woven material in which the mesh of the weave is de- 
pended upon to provide the air passages. In general the individual 
openings thus provided are small and irregular as to shape and 
length. Of course the woven material may be very light, approach- 
ing netting in character, but screens constructed of such materials 
are usually less satisfactory optically. In view of the nature and 
area of the passages provided in certain types of woven screens, 
it is to be expected from the above discussion that unsatisfactory 
acoustic effects may result from their use. Fig. 5 shows the trans- 
mission characteristics of three different woven screens. In this 
figure Curve C represents the effect of a screen of light netting. 
The acoustic properties, it will be noticed, are excellent but the 
screen is probably quite impractical, both optically and mechanically. 
Curve B shows the characteristic of a woven screen of a rather coarse, 
heavy material. Considerable loss is to be noticed throughout 
the frequency range becoming greater at higher frequencies. Curve 
A represents the performance of a still heavier material. The air 



Sept., 1930] 



DESIGN AND TESTING OF SCREENS 



327 



load is apparently too low for efficient transmission and considerable 
loss throughout the frequency range is in evidence. 

In reference to the above discussion and the data presented, it 
appears that the results obtained are consistent with recognized 
acoustic theory, that the satisfactory design of a screen to be inter- 
posed between a sound source and an observer presents no im- 




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FREQUENCY 
FIG. 5. Transmission characteristics of three different woven screens. 

practicable difficulties, and that it is entirely feasible to construct 
a screen which is suitable both acoustically and optically. 

In the above discussion, the transmission data presented were 
obtained in a manner that may be of interest to other workers in 
this field. The method used is only one of a number that might 
be devised, but the results obtained correlate satisfactorily with data 
obtained by listening tests in theaters, and are therefore felt to be 



328 H. F. HOPKINS [J. S. M. p. B. 

quite reliable. The scheme consists essentially of a determination 
of the difference in response of a loud speaker, or other sound source, 
with and without the screen. The response was measured in the 
manner described by L. G. Bostwick in the Bell System Technical 
Journal, Vol. 8, January, 1929. 

In such a test it is desirable that the screen be mounted in the 
same relation to the sound source that it occupies when used in the 
theater and in our work we have stretched it across the mouth of 
one of our theater type loud speakers. In actual use in the theater 
the screen is often spaced a few inches away from the mouth of the 
horn and in such cases the horn may be "boxed in" to the screen 
by means of sound absorbing material. We have made tests to 
determine the effect of spacing the screen at such a distance with 
and without the "boxing" and also to determine the effect of rooms 
of different acoustic properties in which the tests might be made. 
The difference in the indicated performances of a given screen for 
the various conditions was found to be rather small. 

Another consideration in regard to the method of test is that in 
view of the nature of the sound passages of the more satisfactory 
screens it might be expected that some dispersion of the sound might 
result, an effect quite desirable in view of the directional effect of 
all types of commercial loud speakers generally available. The 
dispersion of a few of the screens submitted for test has been measured 
and in some cases was found to be an appreciable factor. In so far 
as dispersion reduces the sound power in the more concentrated 
beam of the source, it is to be expected that tests made on the sound 
axis would show the greatest over-all effect of the screen. 

In view of these effects and in the interests of uniformity, the data 
presented in this paper were all obtained in a relatively small, heavily 
damped room. The screen was stretched directly across the mouth 
of the loud speaker and the measurements were made on the sound axis. 

REFERENCES 

1 JONES, LOYD A., AND FILLIUS, MILTON F.: "Reflection Characteristics of 
Projection Screens," Trans. Soc. Mot. Pict. Eng., No. 11 (1920), p. 59. 

2 JONES, LOYD A., AND TUTTLE, CLIFTON: "Reflection Characteristics of 
Projection Screens," Trans. Soc. Mot. Pict. Eng. X (1928), No. 28, p. 183. 

DISCUSSION 

MR. WEINBERGER: Is it certain that the loss found is due entirely to the 
screen and not partly to the reaction of the screen on the loud speaker? Are 
the losses due to transmission through the screen and partly to a loss of radiation 



Sept., 1930] DESIGN AND TESTING OF SCREENS 329 

from the speaker itself because of reflection from the cloth stretched across its 
mouth? 

MR. HOPKINS: The results which have been shown were obtained under 
conditions representative of actual theater conditions with respect to the rela- 
tive location of the screen and loud speaker, and therefore any effects observed 
should be charged against the screen. 

MR. WEINBERGER: It should be charged to the screen in that particular type 
of loud speaker, but I am interested in a measure of the screen applicable to any 
loud speaker and independent of the action of the screen on the source. We 
have worked on this in RCA Photophone and used a loud speaker back of the 
screen, which was a rather small radiator and placed at some distance from the 
screen so that we were certain there was no reaction from the screen on the 
radiator. I am inclined to be afraid of any measurements with the screen across 
the mouth of such a large horn unless some check measurements have been 
made proving it transmission loss only. 

MR. HOPKINS: Of course some reaction of the screen on the loud speaker 
source may occur, but with relatively long horns, and with a relatively high 
mechanical impedance looking back into the loud speaker unit as is the case for 
the types used in these tests, this reaction might be expected to have a minimum 
effect. With a shorter horn of slower rate of taper, and with a lower mechanical 
impedance this effect might be expected to be more pronounced. In any case, 
the results are more significant if they show the over-all effect of the screen on 
the sound at the observer. The reaction on the source, however, appears to be 
negligible in comparison with the total effect. 

MR. KALGE: I would like to have Mr. Hopkins identify the second sample 
of woven material in a more detailed manner; was the sample representative 
of screens on the market today and was it treated in any manner? 

MR. HOPKINS: The characteristics shown are representative of many screens 
being manufactured at present. No loading was encountered on any of the 
screens considered, except that when necessary they were impregnated with 
flame-proofing material. 

MR. KELLOGG: I notice there are a lot of small waves in the curves of trans- 
mission shown. Isn't it likely that this was due to the reaction of the loud 
speaker? It is difficult to believe that a piece of material would have rapid 
changes in sound transmission of the order of 4 db. for a frequency change of 
only 10 or 20 per cent. It looks plausible that the point raised by Mr. Wein- 
berger might be the explanation of these small irregularities. 

MR. WOLF: I should like to mention a matter discussed at some length by 
the Projection Committee, that is, the deterioration of screen surfaces which 
doesn't effect the acoustic properties of the screen as it does the optical proper- 
ties. At the present time there is no practical method of cleaning screens. A 
method should be devised for making optical measurements on screens every 
three or six months. 

MR. K. D. COOK: In thinking over the curves shown, it does seem as if the 
curves indicate that there was a reaction on the source. I notice that the ir- 
regularities had more or less pronounced separation throughout the length of the 
curves. If it were a matter of the screen alone, it would seem that they should 
come nearer together at the high frequency end, 



330 H. F. HOPKINS [J. S. M. P. E. 

MR. BLATTNER: I believe there is good reason for believing that there would 
be some reflection effects, which would show up but, as Mr. Hopkins shows in 
his data, they are negligible in comparison to other effects. They have been 
observed when using two speakers of radically different design, and therefore I 
think these are chargeable against the screen. 

MR. RAVEN: I should like to ask Mr. Hopkins whether any tests were made 
to determine the variation in screen response when the screen was stretched 
very taut or was limp. I should also like to ask whether any investigation was 
made as to the effect of different filling matter the pigments used in filling the 
screen to make it opaque to light. I have in mind a filler heavily charged with 
some hard pigment in comparison to some filler that was rather soft and not so 
resistant to sound. 

MR. HOPKINS: We have not made any such tests. We are interested only 
in testing commercial screens submitted for approval. I might say that we 
measured the screen under several conditions. We stretched it over a large 
frame and also across the mouths of the horns always at the same tension so that 
it would have widely different vibration characteristics, and the results were 
pretty nearly identical. 

MR. RAVEN: I take it that your conclusion is that whether the screen is very 
taut or hangs limp as a drop hangs, there is no great difference in effect. 

MR. HOPKINS: That is, where the area of the openings is sufficient to give 
good transmission. 

MR. RAVEN: Where the openings were not so pronounced, stretching tended 
to increase the efficiency? 

MR. HOPKINS: Yes, so far as diaphragm action is concerned. 

MR. PARKINSON: The speaker has mentioned transmission as effected by 
total area of perforation. Did he learn anything about the effect of different 
spacing of the perforation? 

MR. HOPKINS: The size of the perforations were all the same; the difference 
in total area was changed by variation of the spacing of the holes. 

MR. PARKINSON: You don't know whether the same area of perforation in 
different sized openings gave the same effect? 

MR. HOPKINS: It is desirable to keep the ratio of the thickness of screen to 
the area of an opening as small as possible. It would be better to make the 
openings large rather than small. 

MR. Ross: Referring to Screen No. 2, what is the natural frequency of the 
screen? At 50 cycles, the curve showed it to be decidedly lower in efficiency, 
and at 100 there was a pronounced increase. Possibly the harmonic periods 
of the screen have a bearing on its transmission. 

MR. HOPKINS: We have no data as to natural period of this screen. Be- 
cause of the construction of the screen, the amount of diaphragm action might 
be expected to be small and therefore the vibrational characteristics negligible. 

MR. JENKINS: I want to ask Mr. Hopkins about his procedure. Did you 
take a known speaker or did you measure the same speaker with and without 
the screen and take the difference? 

MR. HOPKINS: The response measurements of the loud speaker with and 
without the screen were made successively as mentioned. We did not depend 
on the calibration of the loud speaker. 



Sept., 1930] DESIGN AND TESTING OF SCREENS 331 

MR. BRAUN: I wonder if you made any tests which would disclose the amount 
of sound reflected from various screen surfaces in use today. 

MR. HOPKINS: We have not been interested in the screens from that stand- 
point but only in the effect of the screen on the sound at the position of 
an observer. 

MR. SHEA: We have been interested in the acoustical characteristics of screens 
to make sure that adequate sound transmission might be obtained without the 
sacrifice of sound characteristics. Those described are of manufactured screens 
as submitted and the information published was the results of tests rather than 
an attempt to design a screen. The method of test used appears to show the 
difference in sound transmission to the observer in the theater, and that is what 
the exhibitor is interested in. Since the author has shown that the loss due to 
the presence of the screen may be made small, in many cases less than 1 db., 
small variations are of secondary importance. Of course, the method is a differ- 
ence method and the irregularities present in most acoustical room tests would 
show up here. If anyone is concerned much with them, it may be due to the 
fact that he has not noticed that the scale of losses is such that the variations 
are shown up rather markedly as compared to scales normally used for loud 
speaker characteristics. The loud speaker characteristics usually presented 
show more marked variations than do the screens described here. 



RECENT AND FUTURE ECONOMIC CHANGES IN THE 
MOTION PICTURE FIELD 

FRANKLIN S. IRBY* 

"There are," said Mark Twain, "three sorts of prevarication 
plain lies, damn lies, and statistics." 

In the past, engineers have not been as vitally interested in the 
statistics and economics of their particular industries as they are 
beginning to be at the present. It cannot be said, however, that this 
interest has reached a high point as yet, but it is felt that in addition 
to the many technical subjects discussed before this Convention 
a pause to glance at the economic changes in the motion picture 
picture industry would be appropriate. After all, the economic 
changes in the industry affect one's individual welfare, and a review 
of the recent changes, as well as some thought on the future, may 
help to form a better picture of one's personal position. 

Stimulated by the increasing drawing power of the talking picture, 
the motion picture industry experienced in 1929 the best year of its 
history. The wiring of houses for sound pictures progressed rapidly 
here and abroad, and at the close of 1929, there were approximately 
9000 theaters equipped for such pictures, out of a total of 22,600 
in the United States. There were about 2000 sound installations 
in Europe, out of a total of 27,000 theaters. 

The data shown in Fig. 1 give some of the comparative facts 
on sound picture installation. These data are based on the best 
information available on January 1, 1930. Since this date, sound 
installations have progressed at a high rate, as is generally known. 

It is estimated that at least 5500 additional theaters in the United 
States will be equipped for sound during 1930. This will mean that 
75 per cent of all picture houses in this country will have sound 
apparatus by the end of this year. The total installations in Europe 
will probably reach 5000 by the end of 1930, bringing the total 
installations throughout the world to 22,000 or about 40 per cent 

* McGraw-Hill Publishing Company, New York City. (Read before the 
Society at Washington.) 

332 



CHANGES IN MOTION PICTURE FIELD 



333 



of the theaters built. This record-breaking growth will be consider- 
ably slackened at the end of this period, though it is expected that 
installations will continue until all suitable theaters have been 
equipped. Just what will be the final percentage of sound installa- 
tions will depend on language barriers and limiting size of theaters 
in which sound equipment will pay. Satisfactory solutions will 



\Addftional Wired End /930 
\ Wired Sound End 1929 




FIG. 1. Theaters wired for sound vs. total number of theaters. 

ultimately hurdle both these present barriers, and at no distant 
date we may expect a sound equipped theater or no theater at all. 

RISE IN THEATER ATTENDANCE 

It may be of interest to note the rise in attendance at motion 
picture theaters during the past eight years. This is shown graphi- 
cally in Fig. 2. The first sound equipments were installed in the 
latter part of 1926; however, no great public interest was aroused 
until the introduction of the talking picture, The Jazz Singer, in 



334 



FRANKLIN S. IRBY 



[J. S. M. p. E. 



October, 1927. The immediate success of this sound picture was 
the turning point from silent to audible pictures. The phenomenal 
rise in the attendance curve is most marked from this time up to 
the present and many indications point to even higher levels. It 
is conservatively estimated that the total average weekly attendance 



OCT. 1927 Jazz Singer 
Introduced 
Warners Theater/ 

m . 




1922 
FIG. 2. 



1923 1924 1925 1926 1927 1928 1929 1930 1931 
Average weekly attendance at motion picture theaters. 



will reach 125,000,000 by the end of 1931. This is based on the in- 
creased number of theaters that will be equipped, and the better 
quality and wider scope of sound pictures. With the present at- 
tendance of 115,000,000 paid admissions per week, it means that 
practically the entire population of the United States attends the 



Sept., 1930] CHANGES IN MOTION PICTURE FIELD 335 

picture theater once every seven days. It is an accepted fact that 
motion pictures can no longer be considered a luxury, but are a 
necessary form of recreation for the masses. 

The average admission price in the key cities is given as 55 cents, 
while the average for all theaters is approximately 35 cents. Using 
an average admission price of only 30 cents and 100,000,000 as the 
average weekly attendance, it is estimated that the total annual 
paid admissions to American theaters has reached the sum of $1,560,- 
000,000. Of this amount $500,000,000 can be attributed to the 
introduction of sound pictures. 

In contrast with such stupendous figures even for our present 
times, let us consider the early development of the railroads. The 
Baltimore & Ohio Railroad was organized on July 4, 1828, with a 
capitalization of $5,000,000. During the first 50 years of railroad 
development it is estimated that only $400,000,000 was expended on 
construction. Compare this modest sum with the estimated paid 
admissions of $500,000,000 to our movie theaters for the first four 
months of 1930! Times have certainly changed. 

In 1907, there were 5000 theaters in the United States; at the 
beginning of 1930 there were 22,624, representing an average growth 
of about 740 theaters per year. This average has now decreased to 
about 500 new theaters annually. It should be noted, however, 
that the type and size of the new theaters are far superior to the 
earlier theaters. The total investment in the motion picture in- 
dustry has increased year by year until today it is about $2,500,000,- 
000 in the United States. In Europe, the total investment in this 
industry is estimated at $1,000,000,000. Motion pictures, while 
not classified as a manufacturing industry, may be considered as such 
from the point of purchase by the public of entertainment as a 
commodity. Considering this industry in the latter classification 
it now ranks eighth of all manufacturing industries in this country. 

THEATER CHAINS IN THE UNITED STATES 

The earlier theaters in this country were individually owned units. 
It was not long, however, before ownership or control of more than 
single units appeared. This was a natural step, in view of chain 
organizations formed in many other fields. From 1925 to 1930, 
this growth has been particularly rapid. The introduction of sound 
pictures has played an important role in advancing these consolida- 
tions. Referring to Fig. 3, it will be seen that of the total theaters 



336 



FRANKLIN S. IRBY 



(J. S. M. 



in this country, 5805 were operated under chain ownership or control, 
as of January, 1930. There were actually 329 theater chains in 
existence at that time. These chain-controlled units may be classified 
under the following groups: 

12 chains control 50 or more theaters, each 

15 chains control 25 to 50 theaters 
135 chains control 6 to 25 theaters 
167 chains control 6 or less theaters. 



1200 



Legend 

Largest Individual 
-Chains, Jan. 1,1930 - 
A- Paramount- Publix 
B-Fox-Loew 
C- Warner Bros. 
D-R.K.O 



TOTAL 
THEATERS U.S. 




25,000 



20,000 



15,000 



10,000 



5,000 




FIG. 3. Chain controlled theaters in the United States (January, 1930). 



Of the larger chains there are several which are outstanding. 
They are shown to the left in Fig. 3, the number of theaters con- 
trolled indicated in hundreds. It should be noted that of all theaters 
now built, only about 25 per cent are chain controlled, but they 
represent the key theaters throughout the country, and their revenue 
represents approximately 75 per cent of the total. It is expected 
that chain growth will continue at a rapid pace, and by 1935 chains 
large and small will control over 50 per cent of the total theaters in 
the country. 

Economic reasons for the growth of theater chains are many. 
First, they have introduced better theaters, better management, 



Sept., 1930] CHANGES IN MOTION PICTURE; FIELD 337 

and better planned performances. Second, by representing diversi- 
fied investments in various sections of a single city, as well as by 
states, they -have provided greater stability and less risk to the 
investing public. By enabling the building of elaborate and beauti- 
ful theaters, chains have done much to increase the public's theater- 
mindedness. There are other important reasons for this fast chain 
growth, and expectations for future growth. Huge sums have been 
invested by the producing companies in studios and equipment. 
This is particularly true with the advent of sound recording appara- 
tus. It is seen, therefore, that to protect the future outlet for their 
pictures, an assured means of distribution under their personal 
control is necessary. The above reasons, as well as the competition 
for future production outlets, will be the guiding influence in chain 
expansion. 

For the motion picture engineer, these concentrations should 
create a greater demand for his service. The larger chain units 
will undoubtedly build up their own special research and technical 
staffs to handle the increased complexity of mechanical and electrical 
equipment. Such staffs are already in existence for several groups, 
as is well known. 

FOREIGN CHAIN CONTROLLED THEATERS 

Of the 27,000 theaters in Europe, relatively few are under any 
chain control. However, there are some well-organized units in a 
few of the principal countries. In Great Britain, Gaumont controls 
300 theaters; Provincial Cinema controls 150; Associated British 
controls 110; and United Pictures 50. There are a great many other 
chains that control from 6 to 12 theaters; theaters so controlled 
represent, as a rule, the better class houses in key locations. 

The principal theater chains of France are: Pathe-Nathan con- 
trolling 60 theaters; Aubert-Franco-Film controlling 40, and many 
smaller chains of 8 theaters or less. Of the German chains, U. F. A. 
controls 80 theaters throughout Germany, and Bmelka controls 
about 50 theaters. In Italy, Pitaluga has a practical monopoly of 
the most outstanding theaters. In Australia, Hoyts Theaters, 
Ltd., and Union Theaters, Ltd., control 250 theaters together. 

It is worth noting that very recently we have seen American 
capital entering foreign theater control with the acquisition of the 
Gaumont chain in England by William Fox, this control now being 
under the Clarke syndicate. Also, within the past two weeks we 



338 FRANKLIN S. IRBY [J. S. M. p. E. 

have seen a substantial interest acquired in the Kuchenmeister group 
in Germany by Warner Brothers. This group includes Sprekfilm 
of Amsterdam, Tobis of Berlin, Associated Sound Film Industries, 
Ltd., of London, and Compagnie Francaise Tobis of Paris. The 
patents and license involved are those controlled by both the Kuchen- 
meister-Tobis and Klangfilm groups. The latter companies occupy 
an important position in recording and reproduction of sound pictures 
in Germany and Switzerland as well as in other European countries. 
A direct interest in the patents and licenses of the companies involved 
is thus obtained by Warner Brothers. 

Foreign chains, up to the present, have been greatly handicapped 
due to the lack of capital. The European mind has not fully grasped 
the significance of building well designed and attractively decorated 
theaters, as a means of creating a greater public desire for theater 
recreation. Given an opportunity, American capital will introduce 
the most modern of houses and with better showmanship increase 
the theater attendance and profit. 

In continental Europe, there are serious problems still to be solved 
before such a step will be feasible. One is the sluggish attitude 
toward doing things differently from the way they have always 
been done and, secondly, the great fear of having this field taken out 
of their hands. This is understandable, but after all, the masses 
abroad would actually appreciate good entertainment as they do 
here. It would appear practical that a few modern, well managed 
theaters placed in key positions would be a successful stepping stone 
toward the modernization of the European theater industry. 

SOUND PICTURES AND FOREIGN MARKETS 

The enormous increase in the average weekly attendance in Ameri- 
can theaters following the introduction of sound has already been 
shown. The same is true, although to a lesser degree, for the theaters 
in Europe which have been equipped with sound apparatus. With 
theaters throughout the world wired for sound, there are important 
problems of language to be considered to produce the proper pictures 
for our foreign markets. American pictures are now shown in 70 
countries with subtitles translated into 37 foreign languages. 

Heretofore the silent picture was universal in its appeal. The 
print, destined for foreign countries, needed only the translation of 
subtitles in the native language. This, of course, is impossible 
with sound films and, therefore, new solutions have been advanced. 



Sept., 1930] 



CHANGES IN MOTION PICTURE FIELD 



339 



A "double-shooting process" has been used to some extent, in which 
two separate groups of players are used with one story and the same 
group of settings. Another solution, which has been used effectively 
in the case of sound-on-film, is to insert a section of film in the feature 
at certain intervals on which there has been recorded sound in the 
foreign language which describes the picture plot in the same way 
as a master of ceremonies is sometimes used. Another method has 
been to print the subtitles on the picture at requisite intervals, 
and continuing to use the sound reproduction as recorded in English. 
All of these systems have certain drawbacks, and may be considered 



SHOWING EFFECTS OF 
SOUND PICTURE INSTALLATIONS 



Total Export Positive Film 

1929-282,000,000 Feet 
1928-222.000.000 Feet 



AFRICA COUNTRIES 




FIG. 4. American film exports. 

only as temporary expedients. However, where the particular 
foreign market warrants, the use of foreign players in the double- 
shooting process seems a way out for economical production to a 
limited extent. 

Despite this apparent handicap of language, it is interesting to 
note that United States film exports increased 60,000,000 linear feet 
in 1929 over 1928. The total American film exported in 1929 was 
282,000,000 feet of which about 8,000,000 feet was negative film. 
This compares with approximately 1,000,000,000 feet of positive 
film produced in the United States in 1929. It can be seen that our 
foreign markets in the past have been important, and every effort 



340 FRANKLIN S. IRBY [J. s. M. p. E. 

will undoubtedly be made to continue them in the future. In Fig. 4 
are shown some comparative data on American film exports for 1928 
and 1929. The increase in exports for Europe is accounted for by 
the larger number of theaters wired and the demand for talking 
pictures in Great Britain. A 100 per cent increase for Canada is also 
indicated. 

A UNIVERSAL LANGUAGE 

It is estimated that 85 per cent of the motion pictures shown 
throughout the world at present are produced in the United States. 
Of the remaining 15 per cent Germany has 8 per cent of the showing, 
England and France about 2 per cent each, while the remaining 3 
per cent is accounted for by all other film producing countries. 
It should be pointed out, however, that the popularity of sound 
dialog films in continental Europe and other countries in which 
English is not the national language is already beginning to wane, 
while in Great Britain, Australia, and New Zealand they are growing 
more popular. It is obvious that either these countries will have to 
be supplied with the proper type of silent films and a limited number 
of sound films, of the musical type, or else sound films in their re- 
spective national languages. 

Radio broadcasting, though making rapid strides in national 
development during the past eight years, has remained nationalistic 
in character. While international broadcasts are becoming more 
common, without the audience's vision of the scene and corresponding 
action it is felt a universal language will hardly be introduced through 
this medium. On the other hand, it is not too improbable to predict 
that Anglicizing speech throughout the world in decades to come 
can be accomplished by means of the sound films. It is improbable, 
however, to predict this in the near future. 

The universal appeal of American films in the past has been due to 
their improved technic and production as a whole as compared to 
foreign productions. It can reasonably be stated that such will 
hold true in the future with sound recording. Therefore, we have 
every opportunity to maintain these foreign markets by making 
foreign language sound pictures in this country, or controlling 
the making of them abroad, within our own equipped and directed 
studios. A development of the latter will also tie in, perhaps, with 
the development of American chains in foreign countries, as pre- 
viously mentioned. 



Sept., 1930] CHANGES IN MOTION PICTURE FIELD 341 

WIDE FILM DEVELOPMENTS 

After two years of most hectic and revolutionary development, 
the motion picture industry might well pause for breath, but this 
appears improbable. New technical developments that may be 
as far reaching as the introduction of sound are crowding upon the 
scene, and producers must embrace them or be left behind in the race 
for supremacy. The major developments in the offing are: the 
growing use of color and the introduction of wide film. My com- 
ments will be restricted to the introduction of wide film. 

One of the first important economic problems should be settled 
at an early date that is, a standard width for the new wide film. 
Whether this film should be 70 mm., 65 mm., or 56 mm., will be left 
for the discussion of others. However, it is apparent that a standard 
width and other essential dimensions should be agreed on to preserve 
the great advantage of interchangeability of films. 

Our motion picture industry owes its success, in the past, to the 
universally adopted 35 mm. film, which allowed pictures made in 
Hollywood to be shown throughout the world. It should be apparent 
that to require different projection heads and other equipment to 
handle widths of film, other than the present 35 mm. film and one 
standard wide film would not be practical. The introduction of 
the new equipment in this country will probably be slow, and at the 
same time expensive. The same will be true for foreign installations, 
and unless a standard width is agreed upon, serious obstacles will 
arise in the future. 

EDUCATIONAL SOUND FILMS 

The evolution which has taken place from silent to sound pictures 
has opened new doors for the use of films as a means of education. 
Great opportunities lie ahead of the industry for intensive develop- 
ment in this field. Every high school auditorium in this country 
should eventually be equipped with sound projectors. 

In the past, the use of silent films for instruction purposes has 
had a limited application. The advent of successful sound pictures 
is as yet so new that producing companies have not had time to con- 
sider the development of this field. In fact, such companies have 
considered educational films outside the realm of their activities. 

Up to the present, at least, the high cost of sound recording equip- 
ment and the lack of subsidies from the states' and federal educational 
departments have prevented a greater use of sound films for this 



342 



FRANKUN S. IRBY 



[J. S. M. P. E. 



purpose. Quantity production of educational films would lessen 
considerably the costs involved. Some means for equitably distrib- 
uting such costs should be found. Why not seek the aid of the 
individual states and other responsible bodies for such a worthy 
cause? The universal adoption of sound films for educational 
purposes would make it possible to present the finest teachers of 
the country to many audiences. Perhaps the students of tomorrow 



GERMANY 


NUMBER OF THEATERS 


D IOOO 2OOO 3OOO 4-OOO 5O 


DO 














UNITED KINGDOM 














ITALY ^l Z - 40S 


(3.225)* 






RUSSIA ^l 2 - 131 


(7,200)* 






SPAIN ^^^fr g.p 








CZECHOSLOVAKIA '. 2O 










SWEDEN P'* 162 










POLAND 


BH 












AUSTRIA 















BELGIUM 


m*mm 












HUNGARY 


mam---" 












YUGOSLAVIA & ALBANIA 


. 












RUMANIA 


Hi 357 












SWITZERLAND 


~' ' 












FINLAND 


|Z97 












DENMARK 


27O 












NETHERLANDS 


B23 












GREECE 


B224 












NORWAY 


2'2 












BULGARIA 


|I3 




* Includes schools, churches, c/ubs, 
and trovctinq c/nemas that sAotr 


PORTUGAL 


B .30 






motion picttt 


res.. 




TURKEY 


| 104 












LATVIA 


|69 












ESTONIA 


| fcO 












LITHUANIA 


|4S 






Cour-fcsy, Mo+ion Picture 
Division, Dep-h of Commerce 



FIG. 5. Motion picture theaters in Europe (1929). 

will see and hear of the places on the geographical horizon which 
today are confined to the pages of a book. 

The twentieth century has ushered in many outstanding scientific 
accomplishments, the airplane, the radio, the telephone, and many 
others, but none have contributed more to the happiness of the 
human race than motion pictures. They have brought vision, 



Sept., 1930] 



CHANGES IN MOTION PICTURE; FIELD 



343 



romance, and laughter to make life more interesting. Today with 
sound pictures, even those millions throughout the world who cannot 

The Motion Picture Industry Abroad 





Number 
of 
Theaters 


Number 
Theaters 
Wired for 
Sound at 
End of 
1929 


Number 
Theaters 
Built in 
1929 


Number 
Sound 
Studios 
at End of 
1929 


Number 
Sound 
Pictures 
Produced 
in 1929 


Total 
Silent and 
Sound Pictures 
Produced 
in 1929 


Germany 


5,266 


223 


123 


2 


90 


282 


Great Britain 


4,426 


980 


171 


10 


16 


50 


France 


3,113 


166 


20 


5 


4 


52 


Italy 


2,405 


51 


1 


1 





4 


Russia 


2,131 


* 


* 




* 


* 


Spain 


2,074 


25 


10 




3 


20 


Czechoslovakia 


1,200 


15 


50 







( 19 Features 














( 383 Newsreel 


Sweden 


1,182 


45 


7 







* 


Poland 


750 


8 










12 


Austria 


736 


23 










!19 Features 




























160 Shorts 


Belgium 


700 


24 


10 


1 


1 


5 


Hungary 


495 


19 










4 


Jugoslavia 


397 


13 





. . 





Newsreel 


Rumania 


357 


4 


4 







4 


Switzerland 


302 


25 


10 


. 





2 


Finland 


297 


4 


5 







30 Educa'nal 


Denmark 


270 


20 





1 


2 


4 


Holland 


236 


57 


7 







2 


Greece 


224 


6 





. . 





* 


Norway 


212 


8 


1 







3 


Bulgaria 


136 





1 


. . 








Portugal 


130 





6 







!3 Feature 














235 Newsreel 


Turkey 


104 


2 


4 










Latvia 


69 


2 










2 


Bsthonia 


60 


1 


2 


. . 





4 


Lithuania 


45 


1 


1 










Totals 


27,313 


1,722 


433 




116 


1,299 


Latin America 


4,402 


300 


* 


. . 





Negligible 


Far East 


4,000 


400 


Est. 40 







5 












[ 800 


856 Features 


United States 


22,624 


9,000 


500 


. , 


{ 1,000 


1,104 Shorts 












( 150 


174 Serials 












* 


*Newsreels 



* Figures not obtained. 



344 FRANKUN S. IRBY 

read will have the books of knowledge opened to their ears. Today 
the motion picture industry stands at the threshold of new ad- 
ventures. The psychological aspects of the upheaval that has 
just transformed this great industry have not yet been fully realized. 
We can expect greater realism, greater stability, greater accomplish- 
ments, and greater prosperity for the future. 



THE MEASUREMENT OF DENSITY IN VARIABLE DENSITY 

SOUND FILM* 

CLIFTON TUTTLE AND J. W. McFARLANE 

The dependence of the optical density of developed photographic 
materials upon the method of its measurement was first demonstrated 
by Callier. 1 He discussed the effect of light scattering by the photo- 
graphic image and presented data which seemed to justify the em- 
pirical relation: 

D\\ = 



where D\\ (specular density) is the value obtained with the de- 
veloped image in a specular beam, D-ff (diffuse density) the value 
obtained with diffuse illumination, and Q a constant factor greater 
than unity. 

This form of relation holds with practical accuracy for many 
materials though it has since been shown by Bloch and Renwick 2 
and by one of us 3 that an exponential relation fits the facts better 
over an extended density range for the data of Callier and for other 
data on a variety of materials. A theoretical relation involving 
optical constants of the grain clumps proposed by Silberstein and 
one of us, 4 finds excellent experimental justification, and if enough 
information regarding the optical characteristics of the developed 
image was available this relation could be applied to the solution 
of any practical problem. 

DENSITY MEASUREMENTS IN RELATION TO SOUND PICTURES 

In the theory of sound reproduction with the variable density 
method as outlined by MacKenzie, 5 Jones and Sandvik, 6 and others 7 
the measurement of sound track density plays an important part, 
for it is from these measurements that the values of negative gamma, 
positive gamma, and the resultant or over-all gamma are deter- 
mined. 

* Communication No. 435 from the Kodak Research Laboratories. (Read 
before the Society at Washington.) 

345 



346 



CLIFTON TUTTUS AND J. W. MCFARLANS [j. S. M. p. E. 



The value of density which is effective in the reproduction of the 
sound track is neither "diffuse" nor "specular" in the sense that these 
two terms have been used in the literature. So far as we are aware, 
there are no published data correlating "sound-reproducer" density 



.30 



.30 



8 ,10 



33 arc* 



9ATCT 




10 



40 



50 



ao 30 

ANGLE IN DEGREES 

FIG. 1. Distribution of light scattered by positive film of different 
densities (expressed as per cent of normally incident light). 

with either of the aforementioned values. It may be of interest, 
therefore, to consider briefly the matter of density measurement in 
its relation to sound picture projection. 



Sept., 1930] DENSITY MEASUREMENT IN SOUND FILM 



347 



ANGULAR DISTRIBUTION OF INTENSITY FROM POSITIVE FILM ILLUMINATED BY 

PARALLEL LIGHT 

Because of the fact that the photographic image is a nonhomo- 
geneous material formed by clumps of metallic silver grains embedded 
in a matrix of gelatin, the light which is transmitted by the image 
is scattered by reflection and diffraction. Fig. 1 shows distribution 
curves for images developed on motion picture positive film. To 
obtain these curves, the sample was illuminated by approximately 
parallel light and the intensity distribution was read with a photom- 
eter mounted on a spectrometer arm so that it could be rotated 
about an axis passing through the image. The normally trans- 
mitted intensity is so much greater than the intensity a few degrees 




A C 

FIG. 2. Diagrammatic representation of light scattering by photographic 

density. 

away from the normal that it is practical to show only a section of 
these curves in the graph. 

At first glance, distribution curves, such as are illustrated in Fig. 1, 
may be misleading. The relative intensities even at angles close 
to the normal are so small compared to the intensity of the specularly 
transmitted beam that one might feel justified in neglecting their 
effect. These curves are only cross section views of the distribution, 
and to get an accurate conception of the total amount of light scat- 
tered away from the normal, the intensity values given by the ordi- 
nates in Fig. 1 must be multiplied by an area factor which varies 
with the sine of the angle from the normal. 

The following relation may be used to determine the total trans- 
mission from the angular distribution curves: 

90 

= STT 7 e sin 6 A6 

o 



CLIFTON TUTTLE AND J. W. MCFARLANE [J. S. M. p. E. 

in which T Q is the average value of the ordinate over the increment, 
AB. The same relation may, of course, be used to determine the 
effective value of transmission between limits fixed by the solid 
angle subtended at the measured sample by the window of the re- 
ceiving element. 

The significance of light scattering by the photographic deposit 
in the problem of density measurement may be made clear by refer- 
ence to Fig. 2. 

In this figure, parallel light, represented by arrows at the left, 
is incident upon the photographic density, A. The transmitted 
light is indicated vectorially by the arrows at the right of the figure. 
If a printing material is placed in contact with the illuminated 
sample, all of the transmitted light, regardless of direction, 8 is effective 
in exposing the positive material. A measurement of density, to be 
significant for contact printing, must therefore be based upon the 
total transmission, that is, it must include an angle of 90 degrees 
each way from the normal in Fig. 2. This value, which is spoken 
of as "diffuse density," is the value given by most of the commonly 
used densitometers.* 

If the photographic deposit, A, is included in an optical system 
and is imaged by a lens (B, Fig. 2) which subtends a relatively small 
solid angle at A , most of the scattered light is lost and should not be 
included in a measurement of the transmission (or density) if a pro- 
jection print is to be made of the image. Under these circumstances 
the specular value of density (D\\ ) is nearer to the correct value. 

In sound reproduction, with the sample illuminated by light 
from an optical system and with the transmitted intensity collected 
by the window of a photo-cell (represented diagrammatically by C 
in Fig. 2) a value intermediate between the diffuse and specular 
densities is effective. 

DENSITY MEASUREMENT UNDER PRACTICAL CONDITIONS 

Several factors may influence the value of density as measured 
by the photo-cell in the reproduction system. The degree of colli- 
mation of the incident beam of light, the uniformity of the sensitive 
surface of the photo-cell, the quality of the incident radiation, 

* The integrating densitometer, 3 in which the sample to be measured is placed 
over the window of an integrating sphere, and the most common type of densi- 
tometer, in which the sample is placed in contact with a diffusing opal glass, both 
give values of diffuse density in agreement with each other. 



Sept., 1930] DENSITY MEASUREMENT IN SOUND FILM 



349 



the spectral sensitivity of the photo-cell, and probably numerous 
other considerations may have some influence. 

Under conditions which exist in practice, we believe these factors 
to be of small importance in comparison to the effect of altering 
the angle of the cone of transmitted light which is collected by the 
photo-cell. It is nevertheless desirable to state as specifically as 
possible the conditions under which we have made our measurements. 

Fig. 3 illustrates the optical system which was used to illuminate 
the sample with a slit image. This system was built up from stand- 
ard parts and it duplicates the system which is actually used in 
many theater installations. Most of the important dimensions 
are given in the figure. Both lenses, B and D, are of 10.5 mm. 
diameter and the solid angle subtended by the objective lens at the 
density, E, is 31 degrees. 

A potassium photo-cell with a window 25 mm. in diameter was 




FIG. 3. Optical system used in density measurements. 

placed at various distances from the measured sample, thus altering 
the solid angle of the cone of light which was collected. Photo- 
current was measured with a Leeds and Northrup H. S. galvanometer 
calibrated with the cell over the intensity range actually employed. 

A series of densities developed on Eastman positive film in M.P. 
16 to a diffuse gamma of 2.0 was measured. 

A typical set of data is shown graphically in Fig. 4 in which the 
measured values of density are plotted against logio of the half angle 
subtended by the window of the photo-cell at the sample. The 
lowest values of density, D-\\-, were obtained with the Capstaff- 
Purdy densitometer and are shown plotted at the abscissa = logio 
90 = 1.95. 

In most of the reproducers used in theaters, the angle subtended 
by the photo-cell window at the film is about 35 (logio half angle = 
1 .54) . The comparison between the value of diffuse density and the 
density actually measured by the photo-cell in the projector is given 



350 



CLIFTON TUTTLE AND J. W. MCFARLANE [J. S. M. p. E. 



in Table I. For the lower densities the factorial difference between 
the two values is greater, which fact checks the previously reported 
data on positive film. 3 For practical purposes perhaps the Callier 1 
type of relation: 

D R = 



in which D R is the effective reproducer density, will hold with suffi- 
cient accuracy. 






^ 


1.1 I.Z J 13 14 15 1.6 I. 


I LB 1.9 ^ 2.O 



FIG. 4. Density of positive film image as measured by a photo-cell whose 
window subtends various solid angles at the measured sample. (Logio of 
one-half of the solid angle is plotted.) 

TABLE I 

Relation between Diffuse Density and Reproducer Density for Positive Film 



^R 


D-ff 


D R /D 


. 135 


0.07 


1.93 


.37 


.28 


1.32 


.60 


.45 


1.33 


.80 


.62 


1.25 


1.01 


.78 


1.29 


1.20 


.97 


1.24 


1.44 


1.14 


1.26 



Sept., 1930] DENSITY MEASUREMENT IN SOUND FILM 351 

CONCLUSION 

We shall not attempt to discuss the significance of these data 
in any detail, but wish only to point out one or two matters of interest. 

A factorial difference in density determination results in a fac- 
torial difference in gamma. If the reproducer measures a gamma 
value 1 .3 times higher than that determined by sensitometric methods 
employing diffuse densitometry, an audible harmonic may be intro- 
duced. 

Some other factor, such as reciprocity failure which makes the 
sensitometrically determined gamma higher than the negative 
sound track gamma, may partially or completely compensate for 
the effect of higher sound projection gamma. 

A second effect resulting from higher projection gamma is a change 
in the shape of the toe of the H & D characteristic. The toe of the 
characteristic curve which is effective in the semi-specular reproducer 
system will be shorter than that of the curve determined by the 
diffuse densitometer. 

REFERENCES 

1 CALLIER, A.: "The Absorption and Scatter of Light by Photographic 
Negatives, Measured by Means of the Martens Polarization Photometer," 
Phot. J. 49 (n.s. 33) (1909), p. 200. 

2 BLOCK, O., AND RENWICK, F. F.: "The Opacity of Diffusing Media," 
Phot. J., 56 (n.s. 40) (1916), p. 49. 

3 TUTTLE, C.: "The Relation between Diffuse and Specular Density," /. 
Optical Soc. Amer., 12 (June, 1926), p. 559. 

4 SILBERSTEIN, L., AND TUTTLE, C.: "The Relation between the Specular 
and Diffuse Photographic Densities," /. Optical Soc. Amer., 14 (May, 1927), 
p. 365. 

5 MACKENZIE, DONALD: "Sound Recording with the Light Valve," Trans. 
Soc. Mot. Pict. Eng., XII (1928), No. 35, p. 730. 

6 JONES, L. A., AND SANDVIK, O.: "Photographic Characteristics of Sound 
Recording Film," /. Soc. Mot. Pict. Eng., XIV (February, 1930), p. 180. 

7 WATKINS, S. S., AND FETTER, C. H.: "Some Aspects of a Western Electric 
Sound Recording System, " /. Soc. Mot. Pict. Eng., XIV (May, 1930), p. 520. 

8 BULL, A. J., AND CARTWRIGHT, H.: "The Measurement of Photographic 
Density," /. Sci. Instruments, 1 (1923^), p. 74. 

9 CAPSTAFF, J., AND PURDY, R.: "A Compact Motion Picture Densitometer," 
Trans. Soc. Mot. Pict. Eng., XI (1928), No. 31 , p. 607. 



SOUND-PROOFING AND ACOUSTIC TREATMENT OF RKO 

STAGES 

A. S. RINGEL* 

In the production of talking motion pictures, it is generally ad- 
visable to depart as little as possible from the technic that has proved 
so successful in making silent films. We are interested in obtaining 
moving "talkies" and not the "talkie stills," which were only too 
evident in some of the earlier efforts. This effect may be secured 
partly by the use of sound pick-up devices, which permit an actor 
to move about the set at will, and partly by having stages and sets 
of little or no reverberation. 

J. P. Maxfield 1 has shown that reverberation is an important 
factor in helping to create the illusion of depth or perspective in 
sound. But it must be borne in mind that this, if desired, should 
be obtained by proper microphone placing and construction of the 
set itself. There should be none from the rest of the stage. When 
we consider the still relatively poor reproduction of sound in many 
theaters, principally as a result of reverberation, it seems that the 
finer artistic effects thus theoretically obtainable are completely 
overshadowed by the lack of intelligibility resulting from the addition 
of the reverberations in both recorded and reproduced sound. 

A number of other factors must be considered in the construction 
of stages for filming talking motion pictures. These include size 
and number, sound-proofing, provisions for recording, moni- 
toring equipment, ventilating and cooling systems, power outlets, 
and, of course, the relative costs of various materials to be employed. 

Some of these problems have been considered by Humphrey 2 
in a recent issue of the Transactions in which typical E. R.P.I, sound 
recording installations are described. At the RKO Studios, 
RCA Photophone recording equipment is employed, which, be- 
cause of its simplicity and compactness, does not necessitate erection 

* RCA Victor Co., Inc., Camden, N. J. (Read before the Society at Wash- 
ington.) 
352 



ACOUSTIC TREATMENT OF RKO STAGES 353 

of separate elaborate recording buildings. In fact, in most cases, 
the entire recording, mixing, and monitoring equipment is mounted 
upon a small cart, about three feet wide by five feet long, which is 
wheeled into a knock-down booth on the stage. This booth gener- 
ally consists of double walls of Celotex or Insulite, is about 9 ft. 
square, and can be erected in five or ten minutes. The small crew 
of three required to man an RCA Photophone recording outfit is also 
relatively insignificant in comparison with the usual small army 
of stage hands, assistant directors, cameramen, actors, and what not. 

The reproduction of the monitoring loud speaker in these small 
booths is given a sufficiently close approximation to the effect of 
theater reverberation by suitably attenuating high frequency re- 
sponse. Thus, the recordists will exercise greater care in placing 
microphones than when the monitoring speaker is too optimistic 
in output. 

The problem on the RKO lot was first the conversion of some of 
the old "silent" stages, then the erection of newer ones in response 
to the requirements and demands of increased production. It was 
tacitly understood that the former were to be more or less experi- 
mental so far as size, sound-proofing, and acoustic treatment were 
concerned, and to be used as a guide in the design of later ones. 
Thus, some variations in soundproofing and acoustic treatment 
in initial construction were tolerated, and arrangements were made 
for shifting around part of the absorbing material to positions where 
it would be most effective. 

NUMBER AND SIZE OF STAGES 

The number of stages is, of course, determined by the production 
requirements. An average feature picture will take about three 
weeks in the filming and will use two stages almost continuously. 
While "shooting" is in progress on one, sets will be erected on the 
other. Thus, two will permit a production of some 12 or 15 pictures 
per annum, allowing reasonable intervals for retakes. The number 
of stages required for annual production program can thus be readily 
determined. 

In the matter of size, the old silent stages on various lots range 
from about 70 by 100 ft. up to 150 by 300 ft. While the latter is 
unusually large, such dimensions are often required for long shots 
of elaborate sets. It is in this case that the silent pictures must 
make some concession to the sound technic Untreated, the re- 



354 A. S. RINGEL [J. S. M. P. E. 

verberation times are likely to range from about 5 to 15 seconds. 
With a reasonable amount of acoustic treatment, the smaller, which 
have proved most popular, can be brought down to well within one 
second. The larger sizes cannot be considered economical, partly 
in view of the waste space, unused most of the time while a picture 
is being filmed, and partly because of the enormous quantity of 
absorbing material required to reduce the reverberation to a satis- 
factorily low level. 

SOUND-PROOFING AND ACOUSTIC TREATMENT 

Before proceeding further, it would not be amiss to distinguish 
between sound-proofing and acoustic treatment. By the former 
is meant those features of construction that would prevent the 
intrusion of sound originating from the outside. The latter is in the 
form of acoustic absorbing material which is distributed about the 
walls, ceiling, and floors so as to prevent reflection back and forth 
of sound which originates in the room itself. Of course, the absorb- 
ing material will in itself also tend to absorb sounds coming from 
the outside. In the matter of sound-proofing it is necessary only 
to reduce the intensity of intruding noises to a suitable level below 
that caused by "silenced" cameras, working in the open and pro- 
tected by sound-proof hoods or housings. 

OLD STAGES 

The old stages were considered too large to be economical for sound 
picture production and it was decided to divide them into smaller 
sections. In advance of design and construction, consideration was 
given to likely interfering sounds from heavily traveled streets in 
the vicinity, from the carpenter shops just across the studio street, 
and from traffic on the studio street itself. In the presence of all 
these noises, it was decided to use double wall construction in this 
vicinity. 

These stages had been built about 15 years ago and are typical. 
It will be sufficient to take one of those partitioned and describe 
its construction. (A number of other silent stages were treated in 
identical manner.) The over-all dimensions were about 80 by 
175 by 40 ft. The clear height from floor to lowest member of the 
roof truss is 28 ft. The exterior wall consisted of the usual 1 in. 
cement plaster and metal lath over 1 in. wood sheathing, nailed 
across 2 by 6 in. wall studs, 16 in. on centers. The roof is sloping 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



355 



and consists of a composition roofing material over 1 in. wood sheath- 
ing over 2 by 6 in. joists, 20 in. on centers. The floor was of 1 in. 
planking on 2 by 6 in. joists, 16 in. on centers, on 6 by 8 in. beams 
set on joists, resting on concrete piers, 7 ft 11 in. on centers. 

There were a number of doors and windows in the walls and nine 
dormer windows, about 4 ft. square, in the roof. 

The outer walls were retained; all the openings in the sides were 
walled up with the exception of two doorways, 10 ft. 4 in. wide by 



H 



W 





D 

DO 


C D 

a o o 


D a 


D 







*0(1TH SIPC SUeVATlOH 



VfXnc*i-Jittf poors 




FLOOR PLAH OF srate 



FIG. 1. Floor plan of stage scale Vie in. = 1 ft. 

13 ft. 8 in. high, one for each of the partitioned stages. A scene 
dock on one side was not disturbed. A floor plan and elevation of 
the altered stage is shown in Fig. 1. One section is 75 by 107 ft. 
and the other 60 by 75 ft. on the interior. The inside walls are 
separated by an air space of 21 in. from the outer walls, to permit 
entrance of workmen, on all sides except where the scene dock is 
located, where the separation is some 16 ft. 

Wall Treatment. For sound-proofing, the inside face of the original 
exterior walls, including old door and window openings, was covered 



356 A. S. RINGED [J. S. M. P. E. 

with a 15 Ib. waterproof felt and */2 in. Gyplap applied in 4 by 8 ft. 
sheets, nailed 6 in. on center at every stud. The vertical joints 
occurred only at the studding; both vertical and horizontal joints 
were filled in with a standard joint filler, and covered with a heavy 
sticker tape. 

The existing flooring, joists, and girders, where adjoining the 
exterior walls, were cut free and supported on new underpinning. 
The inner walls were supported by 6 by 8 in. girders resting on new 
concrete piers, 7 ft. 11 in. on centers, and are entirely independent 
of the outer walls. The inner wall is of 2 by 4 by 16 in. on center 
studding, with the exterior covered as above with l / 2 in. Gyplap, 
utilizing 4 ft. by 12 in. sheets laid vertically. The space between 
studs was filled in with mineral wool, consistently tamped and held 
in place by a covering of No. 40 cheesecloth, with l 1 /^ in. mesh 
No. 20 galvanized chicken wire over all. For a height of 12 ft. 
above the floor, additional protection to the wall was applied in the 
form of y 2 in. mesh galvanized iron wire screen. A 2 by 6 in. base 
strip, along the floor, and continuous 2 by 6 in. strips at heights 4, 
8, and 12 ft. above the floor served as additional protection. 

Mineral wool was selected as the absorbing material because of 
its relatively low cost, freedom from vermin, and fire resisting quali- 
ties, as well as the uniformly high coefficient of absorption over the 
frequency range. 

The partitioning walls between the two sections of the stage were 
treated in a similar manner. A door opening, 12 ft. by 14 ft. 8 in., 
was left between stages, to facilitate transfer of equipment and sets 
and to enable the cameramen to obtain necessary long shots when 
desired. 

Roof and Ceiling. The roof trusses were rigidly connected to the 
outer walls and presented quite a problem. Both the roof structure 
and inner walls were considered too weak to support the load of an 
additional floating ceiling. Therefore, external sounds setting 
these in vibration are likely to be transmitted to the interior. It 
was also considered impossible to strengthen these members, unless 
at an expenditure of time and money equivalent to the cost of a new 
stage. 

Since the idea of a floating ceiling was dispensed with, the following 
means were taken to make the roof structure more sound-proof 
and sound absorbent simultaneously. On all ceiling surfaces, */2 
in. Gyplap was nailed in 4 by 8 ft. sheets; the seams were not filled 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



357 



or taped. The sloping rafters, on two sides, were furred by 2 by 
2 in. strips spaced 24 in. on centers, and then covered with Gyplap. 
Over the Gyplap were nailed furring strips 8 /4 by 2 in. set 16 in. on 
centers, and then a Vie in. thick layer of Celotex in 4 by 8 ft. sheets. 
A similar furring of 3 /4 by 2 in. strips 16 in. on centers is laid over the 
Celotex and followed by a l x /2 in. thick rock wool quilting, encased 




CO* wvcvs (rof. eprron f 
I f*Tfa*r i*rt:s ) 



FIG. 2. 



Structural details of typical exterior wall and ceiling of sound 
proof construction. 



in 1V 2 in., No. 20 galvanized iron wire mesh, with No. 40 mesh 
muslin on one side under the mesh wire. This quilting is nailed 
over the furring strips, and No. 40 muslin is tightly stretched over 
it and nailed down with wood strips over the furring strips, so as to 
form panels 4 by 8 ft. over the entire ceiling. 



358 A. S. RiNGEL [J. S. M. P. E. 

The laminated structure, with air spaces, aids in the sound-proofing; 
the layers of Celotex and rock wool provide the acoustic damping. 
Additional support is provided for the weighted roof by resting it 
on the inner walls through a strip of cork 2 by 6 in., which acts as a 
shock absorber. These details, as well as those of the wall and roof 
construction, are shown in Fig. 2. Additional muslin is used over 
the rock wool quilt on the ceiling to prevent possible sifting down 
of fine particles of the absorbing material. 

Floors. It had at first been intended to strengthen the floor 
joists and nail another flooring over the old one, in order to prevent 
creaking and drumminess, as well as improve the sound-proofing. 
In the rush to get into production, however, sets were erected on 
the old floor. These, except in only a few cases, were quite free 
from such undesirable effects. It has been necessary at rare intervals 
to caution performers against stamping too hard, or to admonish 
stagehands off the scene. At times in dancing and cabaret scenes, 
a layer or two of 1 in. thick Celotex or Insulite underneath the floor 
of the set would be ample insurance against such unwelcome sounds. 
While the retention of this flooring is not altogether to be approved 
of, it has given surprisingly little trouble, in spite of its rather poor 
condition after the years of battering it had received. 

There is no connection between the floor of one section and the 
other, nor is there any connection between it and the outer walls. 
Thus, hammering and other noises incidental to erection of sets are 
not transmitted or telegraphed from one stage to another. 

Doors and Windows. Even the most elaborate multi-wall structure 
will prove of no use if there are just a few cracks around doors and 
windows. A surprising amount of sound manages to leak through 
even a small opening and special care was taken to insure tight 
fitting joints, with sufficient overlap on doors and windows. Fig. 3 
shows the details of construction of doors that communicate between 
the two sections of the stage and to the outside; also the side 
hinged doors covering the dormer windows. 

The opening between stages is 12 ft. by 14 ft. 8 in. It is closed 
off by two vertically sliding doors of the laminated construction 
shown in Fig. 3. These are raised and lowered by hand, with the aid 
of counterweights. Each door consists of layers of No. 26 galvanized 
iron, 7 /i6 in. Celotex, 2y 4 in. air space, Y 2 in. Gyplap, 7 /ie in. Celotex, 
3 / 4 in. air space, and 7 /ie in. Celotex facing the inside. Grooves at 
the bottom of each door contain 1 in. rubber tubing, and the door 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



359 



sill and jamb are grooved to hold rubber stops. When the doors are 
lowered, pressure is applied so as to force the door against the rubber, 
effectively closing off leaks. 

Openings to the exterior are 10 ft. 4 in. by 13 ft. 9 in. and are also 
closed by two vertically sliding doors of the construction shown in 
Fig. 3. Levers are also employed to press the door against the 
rubber stops on the jamb. 




,-^6 GJ 





/NTERIOR DIVISIONAL WALLS 
Or PARTITION DOORS 



INNE R SC T/OM OF DOORS 





40-14 MUSL IN if SfSH- 

PLAN THRU EXT. DOORS 

% DO Off SHOWN 

ou TER SEC no N or DOCKS 

FIG. 3. Details of door and wall construction. 

The dormer windows are covered by side hinged doors also shown 
in Fig. 3. There is ample overlap and little likelihood of sound 
leaking past them. During a "take" these are generally closed by 
means of a system of ropes and pulleys operated from the door, 
and all the other doors, communicating to the other section of the 
stage and to the exterior, are also shut. 

Ventilation and Cooling. No provisions were made for ventilation 



360 A. S. RiNGEiv [J. S. M. P. E. 

and cooling the old stages other than natural draft through the 
roof vents, which were well baffled. Usually, between "takes," 
doors and dormer windows are opened wide. This arrangement 
is satisfactory when working with moderate sized casts, but with 
large companies, especially when using the additional lighting re- 
quired for color photography, the air conditions soon become un- 
comfortable. In the newer stages, a forced draft is resorted to. 
On rather noisy sets it is not unusual to proceed with doors and 
windows wide open. 

Miscellaneous. Inasmuch as the same roof and roof trusses were 
used to cover both sections of the stage, the sound-proofing of com- 
pressed air, gas, water, and electrical connections was considered 
relatively unimportant; particularly when we compare the relative 
areas that are capable of transferring the sound from one stage to 
another, or from the exterior to the inside. Such connections 
were made in the usual way by the contractors, and have not proved 
to be a source of trouble at all. 

Additional Acoustic Treatment. It is standard practice to erect 
a number of sets on a single stage, so that the director may shift 
from one scene to another with a minimum of delay. This procedure, 
unfortunately, conceals a not inconsiderable portion of the acoustic 
absorbing material on the walls and results in an increase in the 
reverberation time. Exposed reflecting surfaces are bound to cause 
noticeable echoes, too. 

A number of vertically hanging curtains are provided for each of 
the partitioned sections and may be moved to any desired part of 
the stage by means of a system of tramrails and cranes, illustrated 
in Fig. 1. In the larger of the two divisional stages, four curtains 
of 3 / 4 in. ozite are provided, each 35 ft. wide by 25 ft. high. These 
are covered on both sides with burlap, which is securely sewed to the 
vertical sides, top, and bottom, and a l /% in. rope at the top is used to 
suspend the curtain from the tramrail crane. Those on the smaller 
stage are somewhat narrower. As seen from Fig. 1, they may be 
easily moved to various parts of the stage, where their absorption 
will be most effective. 

The construction described has proved to be satisfactory in keeping 
out undesired external noises. Loud sounds from the backfiring 
of a heavy motor truck just outside the door have not disturbed 
recording at all. An exceptionally heavy rainfall did cause some 
trouble, but was not sufficiently serious to halt recording. 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



361 



REVERBERATION TIME AND SOUND-PROOF CHARACTERISTICS 

The calculated reverberation times of the partitioned stages with 
the stage empty and the sliding curtains close to the walls are shown 
in Figs. 4 and 5. The smaller ranges from about 0.5 to 1.0 second, 
and the larger is about 1.0 second. These were calculated on the 
basis of the old reverberation time formula of Sabine, 3 



T = 



005 V 

Sa n 



Upon completion, the stages quite apparently had a lower time than 
computed by the old formula. 



16 



C5 100 1000 5000 

FREQUENCY IN CYCLES PER SECOND. 

FIG. 4. Reverberation time of altered stage, 80' X 110' floor space. 
Rock wool fill between 2" X 4* studs, 16" on centers. Curve 1: using Sabine 
formula, T = 0.05V /Sa a . Curve 2: using Eyring formula, T = 0.05 V/ 




IOO 



1000 



3000 



FREQUENCY IN CYCLES PER SECOND. 

FIG. 5. Reverberation time of altered stage, 60' X 80' floor space. 
Rock wool fill between 2" X 3" studs, 16 "on centers. Curve 1: using Sabine 
formula, T = 0.05V/ Sa a . Curve 2: using Eyring formula, T = 0.05 V/ 
-Slog.(l -a.). 



362 A. S. RINGEL [J. S. M. P. K. 

A recent publication by C. F. Eyring 4 shows that the above equation 
is a special case of the more general equation 

005 F 



T = 



-Slog e (l -aj 



and applies only to relatively "live" rooms, the latter applying to 
both "dead" and "live" spaces. Recalculated on the basis of the 
new formula, the reverberation times are considerably less than a 
second for most frequencies. 

At any rate, we have had no trouble from insufficient acoustic 
damping on these stages. Any deficiencies in the sound pick-up 
in the past have been due to the directors being unacquainted with 
the limitations of the ordinary condenser microphone pick-up. 
Just as we cannot expect to photograph the features of an actor by 
focusing a camera on the back of his neck, so also we cannot expect 
to obtain the fine details of speech due to the high frequency compo- 
nents by locating a microphone behind him (unless, of course, suitable 
reflecting surfaces are provided). With experience, the studio 
staffs have learned of these difficulties and no longer expect results 
from impossible pick-up locations. 

NEW STAGES 

A new stage was erected on a relatively quiet location at one end 
of the studio street, and is 70 by 100 ft. in dimensions. This con- 
tained provisions for a combination viewing and scoring room, 
rehearsal space, offices, library, and the like, as well as the stage 
proper. This had at first been intended for production of silent 
pictures, but was later converted for talking pictures. 

The external wall and roof is of the usual 1 in. Gunnite on 15 Ib. 
waterproof felt, on 1 in. plank, on 2 by 4 in. studs, 16 in. on centers, 
supported on a concrete base running entirely around the stage. 
There is an air space separating the adjacent walls of the stage from 
the scoring room. Each of these walls is of 2 by 4 in. studding with 
1 /z in. Gyplap on the outside. The floor on the stage consists of 
1 by 4 in. tongue and groove flooring, on 2 by 8 in. joists, 16 in. 
on centers. The joists are supported by 6 by 8 in. girders which 
rest on Celotex pads set on 6 by 6 in. posts set on 24 by 24 by 10 in. 
concrete bases in the ground, 8 ft. on centers. A single vertical 
sliding door of laminated construction and with rubber stops was 
provided. 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



363 



Because of its quiet location, it was believed that this construction 
would be satisfactorily sound-proof to external noises and this has 
proved to be true. 

For acoustic treatment, the stage was first lined with a layer of 
7 /s in. thick Celotex over the wall studs and ceiling joists. This 
gave fairly high reverberation times of the order of 2 to 3 seconds. 
The time was excessive, unless modified by the introduction of addi- 
tional hangings. As a result, tests made on a preliminary set were 
altogether unsatisfactory, and the Celotex was replaced with a 
filling of rock wool between the studs. The latter treatment pro- 



REVERBERATION TIME IN SECONDS 

a . . i d 




\ 










NEW SOUND STAGE -70'XIOO' 
WE 1 : CELOTEX ON 3TU05 "XA M XI6"O.C. 
f?VEZ ROCK WOOL FILLING BETWEEN STUDS 






\ 






cu 
w 






\ 












\ 












*% 




, 




























\ 






























x 


\ 
































^ 


s^ 




























^ 


K^_^_^ 
































































^^ 




























'''" 


^--- 


- . 

















~ 


==* 
"^ 






























j 































100 1000 5OOO 

FREQUENCY IN CYCLES PER SECOND 
FIG. 6. Reverberation time of new sound stage 70' x 100'. 



duced reverberation times considerably less than a second over most 
of the frequency range and the stage has given no more trouble 
from this source. (See Fig. 6.) 

Baffled vents at the roof and an exhaust fan system are provided 
for ventilation. 

The experiences with the first stages were made use of in the latest 
to be erected. This consists of a building 150 ft. wide by 447 ft. 
long and is divided into four stages, each 108 by 145 ft. Exterior 
views are shown in Fig. 7. Three of these units have a clear ceiling 
height of 35 ft. from the floor line to the underside of the trusses. 



364 



A. S. RINGEL 



[J. S. M. P. E. 



and the fourth has a clearance of 45 ft. Runways and ventilating 
ducts are located in the trusses above this height. 

The structural framework contains steel columns and trusses. 
The exterior walls and roof are of the typical 1 in. cement on 1 in. 
wood sheathing on 2 by 6 in. studs described previously, with l /z 
in. Gyplap covering the inside of the studding. As before, the inner 
walls and floors are separated from outer walls and from those of the 
other divisional stages. The inner walls are of practically the 
same construction, except that 2 by 6 in. instead of 2 by 4 in. studs 
are employed and filled in with rock wool. This increase in ab- 
sorption is required because of the greater size of the stages. The 
divisional walls between stages are practically the same as the inner 
walls. The floor is raised above the ground to allow for ventilation 




FIG. 7. Bxterior views of new RKO stages. 

below, as in the older stages; and the finished floor is floated on a 
double thickness of Flaxlinum to deaden it. The acoustic treat- 
ment on ceilings, as before, consists of layers of Gyplap, air space, 
Insulite, air space, and 1 in. exposed mineral wool blanket. Bottoms 
of runways are covered with a 1 in. mineral wool blanket to avoid 
reflection. 

Double doors between stages open horizontally and open very 
wide as may be seen from the photographs of the interior, Fig. 8. 
Thus, all the stages may be combined into a single huge room, 
if so desired. Double doors to the outside are located on both sides 
and are operated vertically by hydraulic lifts. 

The stages are ventilated by an exhaust fan system, which changes 
the air completely every seven and a half minutes. Fresh air is 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



365 




FIG. 8. Interior views of new RKO stages. 



366 



A. S. RINGEL 



[J. S. M. P. E. 



brought in under the floor through well baffled and sound-proofed 
ducts of Insulite, lined with a mineral wool blanket to reduce con- 
duction of external noises. The heated, vitiated air is drawn out 
through similar ducts in the rafters. This construction enables 
the running of fans during "shooting" without any disturbance 
from the motors. An individual fan operates in a suction chamber 
for each stage. The reverberation times, as calculated trom Eyring's 
revised formula, shown in Fig. 9, vary from 0.5 to 0.8 second. 

VIEWING AND PROJECTION ROOMS 

The old viewing and projection rooms were revised so as to be 
suitable for listening to talking pictures. A double floor, wall, and 
ceiling construction insulates the projection room from the viewing 



o 

" 



ZI.O 



KX> IOOO 

FREQUENCY IN CYCLES PER SECOND 



5OOO 



FIG. 9. New sound stage 108' X 145'. Rock wool fill between 2" X 6" 
studs, 16" on centers. 



room. The walls of the projection room are of 2 by 4 in. studding, 
16 in. on centers, with J /2 in. Gyplap on the outside and l / 2 in. asbestos 
board on the inside. The adjacent wall of the viewing room is 
similar, except that 7 /] 6 in. Celotex covers the studding on the in- 
terior. 

One of these rooms is 51 by 16 by 9 ft. high, the ceiling being 
somewhat arched. For acoustic treatment, the end walls were 
covered with a 1 in. blanket of mineral wool; the floor carpeted, 
upholstered seats installed, and hangings of Flaggtex placed on rear 
walls and side walls from the rear* extending forward 20 ft. The 
treatment tends to prevent undesirable reflections along the length 
and the audience is located in a relatively dead region, acoustically, 
the advantages of which have been explained by Watson. 5 It was 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 



367 



found that this treatment was not sufficiently satisfactory, and 
peculiar flutter echoes were obtained when clapping hands. Addi- 
tional hangings on the arched ceiling eliminated these effects. The 
reverberation times of this room are shown in Fig. 10. 

Two smaller rooms were also used. Originally, these had a flimsy 
partition between them that could permit cross-talk of sound. 
A new wall was installed between them, consisting of 2 by 4 by 16 
in. on center studding, covered on both sides with 1 / z in. Gyplap. 
A common projection room is used for both these viewing rooms 
and is insulated from them as described before. For acoustic 
treatment in these rooms, which are 7 by 20 by 8 ft. high, 7 /i 6 in. 




100 1000 

FREQUENCY IN CYCLES PER SECOND. 

FIG. 10. Reverberation time of viewing room 51' X 16' X 9'. 



5000 



Celotex on walls and ceiling over 1 in. furring was used, 
reverberation times were well under 0.5 second. 



The 



SUMMARY 



For sound-proofing motion picture stages, light double wall con- 
structions are required in noisy city locations; on quiet spots, a 
single wall is satisfactory. Reverberation times of the order of 0.5 
to 1.0 second are obtained by filling in wall studs with mineral wool 
and using layers of Celotex or Insulite with Balsam or mineral wool 
on the ceiling. Artificial ventilation is provided by use of a separate 
exhaust fan and well baffled ducts for each stage. 

In conclusion, I wish to express my appreciation to Messrs. Dreher 
and Decker, who so kindly made available some of the constructional 
details of the newest stages, and Mr. Carrol Clarke, formerly of the 
RKO Art Department, for his cooperation on the alteration of the 
older stages. 



368 A. S. RINGEL [J. S. M. P. E. 

REFERENCES 

1 MAXFIELD, J. P.: "Acoustic Control of Recording for Talking Motion 
Pictures," /. Soc. Mot. Pict. Eng., XIV (January, 1930), No. 1, p. 85. 

2 HUMPHREY, H. C.: "A Typical Sound Studio Recording Installation," 
Trans. Soc. Mot. Pict. Eng., XIII (1929), No. 37, p. 158. 

3 SABINE, W. C.: "Collected Papers on Acoustics," Harvard University Press. 

4 BYRING, C. F.: "Reverberation Time in 'Dead' Rooms," /. Acoustical Soc. 
ofAmer., 1 (1930), No. 2, p. 217. 

5 WATSON, F. R.: "Acoustics of Buildings," John Wiley & Sons, New York. 

DISCUSSION 

MR. MAXFIELD: I had the pleasure in Hollywood of visiting the stages de- 
scribed, and they are very excellent sound stages. As to his reference to my 
publication a few months ago, the stage should be as dead as possible and the 
reverberation should be built into the studio set. The fact that recorded re- 
verberation adds itself to the reverberation in the auditorium delayed us several 
months. We found that certain of the producers complained and wanted to 
know why they couldn't understand so well when a length of film taken in a 
dead room was connected with another which had been exposed in a room in 
which the walls were treated. It is easy to have both dead and live records by 
changing the microphone position. If you record only the direct sound, you 
can get a sound track without reverberation, but with the microphone farther 
away you get a record with considerable reverberation. In answer to repeated 
questions from the producers as to why with reverberation the reproduction was 
harder to understand when it was pieced with a long shot, we believe another 
factor entered into it the coordination between the ear and the eye. When 
the speaker is present, you listen naturally, and otherwise there is a lack of 
attention. 

MR. RINGEL: I quite agree with Dr. Maxfield in that there should be no 
reverberation on the stages themselves. We should like to cut it down to zero. 
If, for artistic reasons, any is required, it should be obtained from the construc- 
tion of the set itself and by proper microphone placing. But when we consider 
the still relatively poor reproduction of speech in most theaters, principally the 
result of reverberation, it seems undesirable to reduce the intelligibility still 
further by introducing reverberation in the recorded sound. The reproduction 
is much closer to the original when the microphone is located close to the speaker, 
where the direct sound is practically predominant. 

At the present state of development of the art, I believe that this is a psycho- 
logical problem rather than a scientific one. I concede that with perfect re- 
cording and reproducing equipment covering the entire spectrum of sound, and 
with no reverberation at the listener's ears, and with a pick-up of sound on the 
set equal to binaural listening, the effects obtained by the introduction of re- 
verberation in recording will aid considerably in enhancing the illusion. Mr. 
Crab tree's statement referring to loud speakers, "They have a long way to go 
before perfection," applies also to all the other elements in recording and re- 
producing the sound. The artistic effects theoretically attainable on such a 
perfect system result in rather poor reproduction of sound with present-day 



Sept., 1930] ACOUSTIC TREATMENT OF RKO STAGES 

recording and reproducing apparatus. This has been demonstrated by the 
relatively poor naturalness and intelligibility in the long shots of the film pre- 
sented by Dr. Fletcher of the Bell Laboratories. Even in the close-ups, with 
the microphone near-by, Dr. Fletcher's "canned" voice was still far from re- 
sembling his true voice. 

MR. WEINBERGER: I think RKO and RCA Photophone undertook a cour- 
ageous experiment in the design of these stages. When we first worked in Holly- 
wood there were only expensive concrete sound stages in use in other studios 
and RKO decided to try inexpensive light walled stages. They were perfectly 
satisfactory, and the industry owes them, I think, its gratitude for what they 
have done. I hope in the future that this design will be taken advantage of by 
the industry. 

MR. EVANS: I do not know when the work you refer to was done. Warner's 
original sound stage used the light and inexpensive type of construction. I 
question, therefore, whether RKO was the first to use the lighter type of con- 
struction. 



A MODIFIED FILM WAXING MACHINE* 
J. I. CRABTREE AND C. E. IVES 

In a previous communication 1 J. G. Jones described a machine 
for applying a thin line of paraffin wax along the edges of motion 
picture positive film to serve as a lubricant and facilitate the passage 
of newly processed or "green" film through the projector. The 
wax was applied by means of two thin steel disks which dipped 
partly in a pan of melted wax fitted with an electric heater, while 
the film was led over these disks emulsion side down. 

When used for waxing sound film it was found that unless the 
temperature of the melted wax was maintained constant, on cooling 
too much wax was applied and this tended to offset on the sound 
track, thus causing extraneous noises. 

In a subsequent communication 2 a more suitable method of apply- 
ing the wax was described. This consisted in applying a cold solu- 
tion of paraffin wax in carbon tetrachloride by means of an apparatus 
similar to the above. After application of the solution the solvent 
was evaporated by passing through a long tube through which a 
current of warm air was blown. By this method the quantity of 
wax applied is independent of the temperature and depends on the 
concentration of the solution and the peripheral speed of the appli- 
cation disks in relation to the rate of travel of the film. It is thus 
possible to consistently apply a thin wax coating of the necessary 
width which ensures that the sound track is not marred by extra- 
neous lubricant. 

Experiments were then made to adapt the Jones waxing machine 
for the use of the wax solution. The machine was so modified that 
after applying the wax solution the film traveled through a distance 
of about 12 feet before reaching the take-up, but with a 1 per cent 
solution of wax the solvent did not evaporate sufficiently to prevent 
spreading of the wax solution in the wound up roll. By impinging 

* Communication No. 441 from the Kodak Research Laboratories. (Read 
before the Society at Washington.) 
370 



A MODIFIED FILM WAXING MACHINE 



371 



a current of hot air against the film it was possible to evaporate a 
sufficient quantity of the solvent, but it was desired to eliminate 
this auxiliary drying apparatus if possible. 

Further tests indicated that by using a more concentrated wax 
solution (5 to 10 per cent) and by rotating the disks more slowly 
the auxiliary drying apparatus was not necessary. With a 10 per cent 
wax solution and a rate of travel of the film equal to 180 feet per 
minute, satisfactory applications were obtained with the peripheral 
speed of the disks equal to one-fifteenth that of the travel of the 
film. 




FIG. 1. Modified Jones wax applicator. 

With this procedure the resulting wax coating was somewhat 
soft when wound in the roll owing to incomplete evaporation of 
the solvent, which caused a slight offsetting of the wax on the base 
side of the film. This is desirable, however, because both sides of 
the film require lubrication in the projector. 

Conical cinching of the film would tend to make the wax coating 
wander onto the sound track, but in such an event the coating of 
wax is so thin that the extraneous noises thereby produced would 
be of negligible magnitude. Exhaustive ground noise tests with 
film waxed in the manner indicated have shown that in practice 
the waxing procedure does not introduce extraneous noise. 



372 



J. I. CRABTREE AND C. E. IVES 



[J. S. M. P. E. 



The Jones machine modified for the application of a wax solution 
instead of melted wax is shown in Fig. 1. The new parts required 
are (a) a feed sprocket, (b) new application disks (0.15 in. thick), 
(c) new wax pot, (d) tank for holding wax solution fitted with feed 
pipe, and (e) one reducing and reversing gear for driving the appli- 
cation disks. The old hood and electric heater are discarded and the 
machine rewired. 

A close-up view of the application disks and wax pot is shown in 
Fig. 2. The pressure roller, R, serves to maintain good contact 



: 




FIG. 2. Close-up view of application disks and wax pot. 



between the blades and the film, while the window in the side of the 
tank affords a check on the volume of the liquid. 

Under operating conditions the wax tank is fitted with a cover but 
even under these conditions considerable evaporation of the solvent 
takes place and it is necessary to keep a dilute replenishing solution 
in the reservoir which has a concentration equal to half that in 
the tank proper. For example, when using a 10 per cent solution of 
wax in the applicator tank, the reservoir tank should contain a 5 
per cent solution. 



Sept., 1930] A MODIFIED FILM WAXING MACHINE 373 

REFERENCES 

1 JONES, J. G.: "A Film Waxing Machine," Trans. Soc. Mot. Pict. Eng., 
No. 15 (1922), p. 35. 

2 CRABTREE, J. I., SANDVIK, O., AND IvES, C. E.: "The Surface Treatment 
of Sound Film," /. Soc. Mot. Pict. Eng., 14 (March, 1930), p. 275. 

DISCUSSION 

MR. HUBBARD: It seems to me that the solution used to give the proper 
lubrication with the Dworsky machine might give the same lubrication as this 
modified Jones machine. The only objection to the wax solution all over the 
film is that it is subject to finger prints and marks in handling, and this would 
not apply so much to this type of machine. I should like to ask whether the 
parts for this can be obtained to apply to the present Jones waxing machine. 

MR. IVES: Yes, the parts can be obtained, and it is only necessary to drill a 
few holes in the casting for the supply tank. It is better to use hard wax for 
application over the entire surface so that dirt doesn't become imbedded and 
increase ground noise, but any wax for surface coating is not satisfactory from 
the viewpoint of lubrication. Nothing is better than paraffin for lubricating. 

MR. W. B. COOK: Do you use carbon tetrachloride, and if so, do you have 
difficulty with a solution of 5 or 10 per cent? Doesn't it tend to separate? 

MR. IVES: If you chill a 10 per cent solution to 30F. or 40 F. some of the 
wax will come out of solution. 

MR. COOK: We found it did and we abandoned the wax and used oil. It 
served the purpose equally well or better. 

MR. IVES: It is more likely to smear and after oil has been smeared on the 
sound track it accumulates dirt rapidly. Precipitation of the wax may have 
been due to moisture. 

PRESIDENT CRABTREE: Drying the carbon tetrachloride with calcium chloride 
will eliminate the water. 



THE PROCESSING OF VARIABLE DENSITY SOUND 
RECORDS 

R. F.NICHOLSON* 

Before consistent faithful reproduction can be accomplished 
with the variable density system of recording, it is necessary to de- 
termine the proper exposure range and development of both the 
negative and the print. Predetermined characteristics have proved 
a help in determining these factors. 

A half dozen sensitometric strips were made, respectively, on various 
negative and positive emulsions. They were developed in the par- 
ticular developer being investigated. The developments were 
so timed that the entire contrast range ot the developer was com- 
pletely covered. The density readings were made on a Martens 
densitometer using diffused light. The portions of the Hurter and 
Driffield characteristics, falling within the exposure range of the 
particular recording system, were replotted on linear coordinates 
with the diffuse transmissions as ordinates and the exposure as 
abscissas. In a system such as the Western Electric uses, the ex- 
posure range can be made to cover the entire characteristic. In 
most of the flashing lamp systems, however, there is a limit to the 
available light range. 

Fig. 1 shows a characteristic of Eastman Panchromatic negative, 
Type II developed in M. Q. borax to a gamma of 0.78. The positive 
characteristic in quadrant III is of Eastman Cine positive developed 
in M.P. 16 to a gamma of 2.15. The respective contrasts of negative 
and print roughly approximate standard commercial developing. 
Within certain limits, the exposure of a point on the print in a contact 
printer is proportional to the diffuse transmission of the corre- 
sponding point on the negative. Therefore the ordinates of the 
negative characteristic and the abscissas of the print characteristic 
are linearly related and it is possible to graphically predetermine 
the over-all characteristic of print transmission versus negative 

* 106 W. 56th St., New York, N. Y. (Read before the Society at Washington.) 
374 



PROCESSING OF SOUND RECORDS 



375 



exposure for any printer exposure, without actually making a print. 
The abscissa of a point on the over-all characteristic is equal to 
the abscissa of the corresponding point on the negative characteristic. 
The ordinate of this point is determined by projecting from quadrant 
I to IV, through quadrants II and III. The slopes of the straight 
lines in quadrant II vary inversely with the exposure of the pi inter 
light. By this method the over-all characteristic for any printer 
setting can be predetermined for all possible combinations of negative 
and positive characteristics. If 3.75 is the unmodulated negative 




FIG. 1. Tone reproduction diagram for Type 2 Panchromatic negative 
developed to a gamma of 0.78. 

exposure, the over-all characteristics obtained in Fig. 1 by varying 
the printer exposure, vary in unmodulated print transmission from 
20 to 70 per cent. If we consider for the moment, that the negative 
exposure is directly proportional to the signal to be recorded and the 
print transmission is directly proportional to the reproduced signal, 
the proper processing for true reproduction can be determined from 
these characteristics. If extreme care were taken in their plotting 
they could be analyzed and the respective levels ot the various 
harmonics determined. However with the following considerations 
sufficient information can be obtained by mere inspection. The 
closer the characteristic approaches a straight line, or a linear relation 



376 



R. K. NICHOLSON 



[J. S. M. P. 



between negative exposure and print transmission, the less will be 
the film distortion. If the sound lamp intensity remains constant 
the volume of the reproduced signal is proportional to the range of 
modulation of print transmission, thus it will increase with the slope 
of the characteristic. The ground noise, due to accumulated particles 
of dirt on the positive, will increase with an increase in the un- 
modulated print transmission. However this is no inducement for 
lowering the print transmission as practically the same result could 
be accomplished by reducing the intensity of the sound lamp. The 




FIG. 2. Effect on the over-all characteristics of varying negative 
development. 

noise level from this source would be independent of the unmodulated 
print transmission if the sound lamp intensity were adjusted to 
maintain a constant unmodulated exposure of the photo-cell. 

Of these characteristics, A and B would reproduce most faithfully 
if the negative exposure range were from 2 to 7. With characteristic 
F, however, a signal of equal volume with only a small loss in quality 
could be obtained by modulating from 0.05 to 1.1. The recording 
level would be down 14 db. and the unmodulated exposure would 
be decreased 89 per cent. These are important reductions when 
portability is an essential factor in the design of the recording equip- 
ment. 



Sept., 1930] 



PROCESSING OF SOUND RECORDS 



377 



The effect on the over-all characteristic of varying the negative 
development is shown in Fig. 2. The negative characteristics 
are of Eastman Panchromatic Type II, developed, respectively, 2, 
4, 8, 12, and 20 minutes in M.Q. Borax. The corresponding gammas 
are 0.20, 0.35, 0.60, 0.78, and 0.98. The positive characteristic 
is the same as was shown in Fig. 1, Eastman Positive developed four 
minutes in M.P. 16 to a gamma of 2.15. In predetermining the 
over-all characteristics the printer lines are so drawn that the un- 
modulated print transmissions are all 40 per cent if we again consider 




FIG. 3. Effect on over-all characteristic of varying positive development. 



3.75 as the unmodulated negative exposure. Comparing the char- 
acteristics over an equal signal output or print transmission range, 
characteristic, A , with the maximum negative contrast, would prob- 
ably produce the most faithful record. It possesses the added ad- 
vantage of the least negative exposure range or recording level, 
reducing to a minimum the distortions due to overloading in the 
exposing system. 

In Fig. 3 the effect is shown of varying the positive development 
with a constant negative development and unmodulated print 
transmission. The Eastman positive characteristics represent re- 
spective developments of 2, 4, 6, 8, and 12 minutes in M.P. 16 at 



378 



R. F. NICHOLSON 



[J. S. M. P. E. 



G5F. The corresponding gammas are 1.38, 2.15, 2.33, 2.39, and 
2.63. The negative characteristic is the same as was used in Fig. 1, 
Eastman Panchromatic Type II developed twelve minutes in M.Q. 
Broax to a gamma of 0.78. As in Fig. 2, the printer lines are ad- 
justed in each case to give an unmodulated print transmission of 
40 per cent. The change in the shape of the over-all characteristics, 
due to the variation in the positive development, is so slight only 
the characteristics of the maximum and minimum development are 
shown. The remaining characteristics fall within the envelope 




FIG. 4. Effect on over-all characteristic of varying negative development 
using Par Speed negative. 

formed by these two curves. The mutual gamma varies from 1.0 
to 2.0 with practically no apparent change in volume or quality. 

In Fig. 4, the negative characteristics are of Eastman Par Speed 
negative developed 2, 4, 6, 10, and 15 minutes in M.Q. Borax to 
the corresponding gammas of 0.28, 0.58, 0.96, 1.31, and 1.60. As in 
Fig. 2, the Eastman Positive characteristic is used, developed 4 
minutes in M.P. 16 to a gamma of 2.15. The results show an in- 
crease in slope with an increase in negative contrast, checking 
the results obtained in Fig. 2 with Eastman Panchromatic Type II. 

These results tell nothing of the effects due to grain and resolving 
power but considerable knowledge is gained of the linear distortions 



Sept., 1930] 



PROCESSING OF SOUND RECORDS 



379 



and volume changes due to film processing. The results are not 
directly applicable to a sound recording system without some modifi- 
cations. Usually there is some distortion in converting the amplified 
signal voltage into a modulated light intensity. Thus the negative 
exposure is not always directly proportional to the amplified signal; 
nor is the diffused transmission of the print a linear measure of the 
exposure of the photo-cell when the film is projected. It would 
seem that these transmissions would more closely approximate 



IOQ 



40 



7. 



o 

10 20 30 40 50 60 70 80 90 100 
DIFFUSE TRANSMISSION 

FIG. 5. Relation between diffuse and specular transmission. 

the exposure of the photo-cell if they were actually read in the pro- 
jector by inserting a micro-ammeter in the photo-cell circuit. 

In Fig. 5 the relation between diffuse and specular transmission 
is shown. The transmissions as read in a projector fall approxi- 
mately midway between the two, showing that the light is neither 
wholly diffused nor absolutely parallel. 

DISCUSSION 

MR. MAXFIELD: I should like to have some advice from Dr. Nicholson. I 
understand this paper applied only to the newsreel work in which the sound is 



380 R. F. NICHOLSON 

recorded on the same film as the picture. In the studios a separate film is used 
for the sound negative. 

MR. NICHOLSON: The results I have indicated are applicable to either the 
single or double system of recording. In the double system where a separate 
negative is used to record the sound the negative development is not limited to 
contrasts suitable for picture negatives. Unfortunately I have no slides in- 
dicating the results of recording on positive stock. For a given range of negative 
exposure the volume of a record made on positive stock can be quite in excess 
of a record made on panchromatic or negative stock. This is probably due to 
the higher contrast range of the positive stock. 

MR. CARLTON: Perhaps I didn't follow you closely but you might clarify 
things for me by stating the respective contrasts which you found to give the 
best reproduction when recording on panchromatic stock and printing on regular 
positive stock. 

MR. NICHOLSON: These results would not indicate the answer to such a 
general question. The slides showed the effect of varying the negative and 
positive contrasts but only for a single unmodulated negative exposure and a 
single positive print transmission. As was shown in Fig. 3, the contrast of the 
print had practically no effect on the over-all characteristic. 

MR. MAURBR: Did I correctly understand your statement with regard to 
the independence of the positive contrast and the over-all characteristic? As I 
understand, that is true provided the exposure is adjusted so that the unmodu- 
lated print transmission is maintained constant. 

MR. NICHOLSON: Yes, Fig. 3 showed that if the print exposure is adjusted 
to maintain a constant unmodulated print transmission, the variation in print 
contrast has practically no effect on the over-all characteristic. 



A SILHOUETTE STUDIO 

C. FRANCIS JENKINS* 

As many of the members of the Society of Motion Picture Engi- 
neers are aware, the Jenkins Laboratories have been broadcasting 
radiomovies from 8 to 10 P.M., E. S .T., every evening, except Sun- 
days and holidays, for nearly two years. 

Judging from the reports we receive, our broadcasts are giving 
novel amusement, though we have no very accurate way of knowing 
how many there are who are nightly entertained by our picture 
stories. 

Perhaps we are warranted in assuming that of the hundred 
thousand neon lamps which have been sold since we began our 
broadcasts, at least one out of every five is in actual use in a radio- 
visor. Such an assumption seems warranted by collateral evidence, 
and from the reports we get from all over the United States, from 
Canada, Cuba, and Mexico. 

We have been using black and white figures almost wholly, namely, 
silhouette or "cartoon pictures." For such broadcasts, we purchased 
some of the cartoons used in the film theater ; and we also had some 
films made specially for our use by professional movie cartoonists. 

Perhaps it may not be amiss to say here that the word "cartoon" 
in films was doubtless originally adopted from the old newspaper 
drawings in black and white figures, made by pen and ink, in ex- 
aggerated character. The adaptation of this pen and ink drawing 
to the telling of a movie story in continuity over a short time period 
has proved entertaining to many millions since. 

But these pen and ink movies are too costly for us, because the 
whole cost has to be charged to our single broadcast station. The 
cost to theaters is divided by renting to many theaters. But this 
opportunity of subdividing the cost is not yet open to us. Our 
one broadcast station must absorb it all. This is prohibitive. 

* Jenkins Laboratories, Washington, D. C. (Read before the Society at 
Washington.) 

381 



382 C. FRANCIS JENKINS [J. S. M. P. E. 

So we decided to set up a silhouette studio, for the making of car- 
toon movie stories at the same speed at which regular halftone 
movies are made. Consequently the labor cost is greatly reduced, 
i. e., reduced to only a very small fraction of the cost for the movie 
story in pen and ink. 

So far as I am aware, this silhouette, or cartoon studio, is unique ; 
and it is thought that perhaps a description of it, and the scheme 




Jenkins Silhouette Radiomovie Studio. 

(The camera included in the picture is actually never as near the subject 
as here shown.) 



of its employment may be of service to others of our membership 
Much of the detail of the set-up is shown in the illustration here- 
with. There is a smooth white wall-surface, illuminated by incan- 
descent lamps at the sides, top, and bottom. This produces smooth 
illumination of the background, while direct light from the lamps 
cannot fall on the performers because of the shields set up for that 
purpose. We are, therefore, photographing the lighted background 
only, and figures between this lighted ground and the camera block 



Sept., 1930] A SILHOUETTE STUDIO 383 

out portions of the ground to build up silhouettes of such figures. 

The top of the platform on which our "stars" perform is elevated 
about a foot above the floor level, and is located 4 feet 6 inches from 
the illuminated background. 

The camera lens we had available had too long a focus for the short 
length of the studio room, so we set up a mirror at the end of the room 
opposite the platform, and photograph our performers by reflection 
in the mirror (not shown in the photograph). In effect the mirror 
increased the length of the room by ten feet. 

Obviously, when we photograph automobiles, flying machines, 
railway trains, fences, houses, and the like, minature cardboard 
figures of these are made and drawn across the lighted area on wires, 
while the camera photographs them from a nearby position which 
will make the figures properly proportioned to the living actors 
which are to appear in the same scene when the two are doubled in 
the printer. 

We have found, as many another movie director has found, 
that if there is a mental suggestion on the mind of the observer, 
the thing itself does not need to be so very realistic to convey a 
perfectly satisfactory story. Thus, crossed wires were used to slide 
the airplane upon, causing the plane to loop-the-loop in such fashion 
as to produce a real thrill, especially when the pilot's sweetheart 
on the ground registers fear as he starts into the loop, and relief 
when he pulls the plane out of the loop close to the ground, and 
makes a perfect landing. 

I did not spend much money on this studio, because we shall doubt- 
less be setting up another soon to make radio "talkies," in halftone 
pictures and with appropriate dialog and sound. 

However, the silhouette radiomovie stories are so unique, and so 
realistically clever, I think we shall give them up with a feeling of 
regret. They are as catchy and entertaining as the page of Sil- 
houettes in the Ladies Home Journal, plus the action which com- 
pletes the continuity of the story. 

These silhouette radiomovie stories have come to have so fas- 
cinating an appeal to our broadcast audience that many seem re- 
luctant to approve, just yet, our proposed change-over to halftones. 
While those who have seen our silhouette talkies find them doubly 
entertaining because of the realism of their story presentation. 

It has Occurred to me that perhaps these silhouette movies might 
be of interest to the theaters not yet changed over to the "talkies." 



384 C. FRANCIS JENKINS 

I believe their novelty would catch the public fancy. They certainly 
present a movie story in a very catchy fashion. 

DISCUSSION 

PRESIDENT CRABTREE: A few years ago I invested $2.50 in one of the Jen- 
kins televisors but I didn't have much success with it. I am interested to know 
whether it was due to my dumbness or whether it is possible to maintain syn- 
chronism for any length of time. What is the longest time that anyone has kept 
the picture in synchronism with one of the friction drives such as you recom- 
mend? 

MR. JENKINS: It is possible to run a whole picture without touching the 
synchronizing screw. The radiovisors now are smoother than the first, but it 
is astonishing that that simple little apparatus will produce synchronism. I 
shall be delighted if any of you will put it to your own test. 

MR. Ross: I should like to say that if Mr. Crabtree used his motor on Roches- 
ter power obtained from Niagara this failure to obtain synchronism is not sur- 
prising. The frequency of the supply varies from 59 to 61 or even 62 over a 
period of a few minutes. 



ABSTRACTS 

The Editorial Office will welcome contributions of abstracts and book reviews 
from members and subscribers. Contributors to this section are urged to give 
correct and complete details regarding the reference. Items which should be 
included in abstracts are : 

Title of article 

Name of author as it appears on the article 
Name of periodical and volume number 
Date and number of issue 
Page on which the reference is to be found 
In book reviews, the following data should be given: 
Title of book 

Name of author as it appears on the title page 
Name of publishing company 
Date of publication 
Edition 
Number of pages and number of illustrations 

The customary practice of initialing abstracts and reviews will be followed. 
Contributors to this issue are as follows: E. E. Richardson, Clifton Tuttle, and 
the Monthly Abstract Bulletin of the Kodak Research Laboratories. 

Densitometer an Automatic Timer. S. E. SNYDER. Intern. Phot., 1, December, 
1929, p. 8. In this negative timing device, the film passes under a light measuring 
device (probably a photo-electric cell) which gives direct readings of the light 
transmission of an entire frame or a portion of it. These readings are expressed 
in terms of printer light settings. Thus the instrument eliminates the need of 
development of test strips necessary with the usual negative tinier. The machine 
is equipped with a footage counter, electromagnetic scene counter, and meters 
for checking the current supply. It may also be used for timing variable density 
sound records. Kodak Abstr. Bull. 

Review of American Film Technique. W. GEYER. Kinotechnik, 11, Dec. 5, 
1929, p. 623. The author finds that the American film industry has made a tre- 
mendous advance since his visit years ago. The principal cameras used are 
Bell & Howell and Mitchell, both of which are briefly discussed. Panchromatic 
negative is most generally used. About 50 per cent of the negative is developed 
on racks or dums and 50 per cent on machines. The principal types of developing 
machines are discussed and illustrated. These are: sprocket driven machines 
with idle rollers for take-ups, sprocketless machines with loops controlled by auto- 
matic take-ups, sprocketless machines, each shaft of which is driven by an oil 
turbine and having the speed of the various parts controlled by a valve in the oil 
line which is governed by the rising or falling of an idle roller, the Spoor-Thompson 
machine, also sprocketless, which is driven by the lower set of rollers instead of 
the upper, and the Fearless machine in which some rollers are fixed and some are 

385 



386 ABSTRACTS [J. S. M. p. E. 

loose upon the same revolving shaft The degree of development in all these 
machines is controlled by speed and not by the quantity of film in the developer. 
The Bell & Howell printer was the only printer used for sound work, and both 
Bell & Howell and Duplex printers were used for pictures. Variable width and 
variable density sound film are briefly discussed. The important color film 
processes are taken up. For Technicolor pictures 50 per cent of the cameras are 
Bell & Howell or Mitchell. Wide film is briefly mentioned. Kodak Abstr. Bull. 

Wide Film Prospects. C. E. A. Committee on the Large Screen. Kinemat. 
Weekly, 157, March 20, 1930, p. 67. The Fox Grandeur film (70 mm.), the Para- 
mount Magnafilm (56 mm.), and other new widths are described. The Fear sys- 
tem uses standard stock but the picture is taken with its width along the film 
and occupies the space of approximately two and a half of the standard maskings. 
An optical device rectifies the image for projection. The Committee considers 
that standardization will be achieved before any general adoption is called for, 
and that standard films will be exposed on "sets" simultaneously with the wider 
films, so as to satisty the remaining demand for the smaller prints. Kodak 
Abstr. Bull. 

Transmission of Sound by Walls. P. E. SABINE. J. Acoustical Soc. Amer., 1, 
Part 1, January, 1930, p. 181. A great number of measurements were made with 
different wall materials leading to the conclusions that: (1) For solid single walls, 
the per cent reduction in sound is proportional to the logarithm of the weight per 
unit area. (2) For double walls entirely separated, the thickness of the air separa- 
tion is most effective in increasing absorption and the use of sawdust or other 
fillers decreases the effectiveness of insulation. (3) For double walls, partially 
connected or bridged, filling increases the insulation about as much as would be 
expected from the increase in weight. (4) By far the best way of increasing the 
effectiveness of "sound proofing" is to decrease the area of "contact points" 
between inner and outer walls. Kodak Abstr. Bull. 

Optimum Reverberation Time for Auditoriums. W. A. MACNAIR. J Acousti- 
cal Soc. Amer., 1, Part 1, January, 1930, p. 242. The variation in reverberation 
time with fr< quency should be such that sounds of equal apparent loudness die 
out in equal times. This leads to an absorption characteristic similar to thai 
produced by an audience, thus checking observations that well filled auditoriums 
are acoustically good. A modification of Sabine's formula more applicable to 
small rooms is developed and seems satisfactory in practice. Kodak Abstr. Bull 

Hearing of Speech hi Auditoriums. V. O. KNUDSEN. J. Accoustical Soc. Amer., 
1, October, 1929, p. 56. The author considers the four acoustic qualities of a room 
to be size, shape, reverberation time, and extraneous noises.' He then shows thai 
maximum "articulation" or intelligibility of speech occurs at a level of 70 decibels 
above the noise or threshold level and for good results a speaker should not fall 
below 50 decibels. Most speakers fall below this in large auditoriums. The rever- 
beration time for speech is noticeably different from that for good reproduction 
of music, necessitating a compromise in practice. Even if designed specially for 
speech, auditoriums larger than 400,000 cubic feet should have amplifying systems 
for all speakers. Kodak Abstr. Bull. 

Beats and Related Phenomena Resulting from the Simultaneous Sounding of 
Two Tones. II. E. G. WEVER. Physiol. Rev., 36, November, 1929, p. 512. This, 
the second paper on beats, contains a review of the phenomena of beats, conditions 



Sept., 1930] ABSTRACTS 387 

for their excitation, their subjective nature, and their relation to auditory theory. 
Kodak Abstr. Bull. 

Frequency Characteristics of the Light Variation in the Sounding Arc. J. JAU- 
MANN. Z. Physik, 59, No. 5-6, 1930, p. 386. A carbon arc was modulated by os- 
cillations of frequency 100 to 50,000 per second and the resulting variations in the 
brightness of the positive crater and the arc itself measured with a photo-cell. The 
results indicate that such an arrangement would be suitable for light telephony. 
Kodak Abstr. Bull. 

Should Non-Flam Be Enforced? Bioscope, 83, April 23, 1930, p. 35. In the 
House of Commons, Captain Todd asked the Secretary of State for the Home 
Department, whether he was aware that there was on the market a British-made 
film base which was guaranteed fireproof, and whether the Government was pre- 
pared to consider the question of making the use of British non-inflammable films 
compulsory. In reply, the Home Secretary stated that he was not aware that any 
non-inflammable film had been yet produced which would fulfill the requirements 
of the cinema industry, and that he could not add anything at present to his reply 
given on January 23, last. Kodak Abstr. Bull. 

Safeguarding the Storage of Photographic, Motion Picture, and X-Ray Films. 
C. R. BROWN. Radiology, 14, May, 1930, p. 454. The discussion includes the 
effects of various temperatures upon the decomposition and ignition of cellulose 
nitrate film, the composition and toxicity of the decomposition products, and 
storage requirements under various conditions. Kodak Abstr. Bull. 

Cellulose Nitrate and Acetate Film. A. H. NUCKOLLS. Projection Eng., 2, 
June, 1930, p. 24. A general discussion of the temperature values at which film 
ignites (for nitrate 230 F. to 300 F. and for acetate 700 F. to 800 F.); the 
type of decomposition (nitrate self-supporting or exothermic, acetate, endo- 
thermic) ; and the products of combustion (for nitrate the products are extremely 
poisonous, for acetate the effect is not so injurious). The author points out the 
relative ease of extinguishing a fire of burning acetate in comparison to the diffi- 
culty involved in putting out a fire due to nitrate film. E. E. R. 

Two-Way Television. H. E. IVES. Bell. Lab. Record, 8, May, 1930, p. 399. 
A permanent installation of television equipment and circuits has been set up be- 
tween the Bell Laboratories and the American Telephone and Telegraph Com- 
pany's offices, two miles apart. Speakers face a screen and talk into a microphone 
just back of it so that the entire face is visible to the other party. Listening is 
through a loud speaker carefully placed to avoid reaction with the microphone 
in the same booth. An improved 5000 element picture is transmitted, requiring a 
transmission band 4000 cycles wide. Blue light is used for scanning in transmis- 
sion so that the observer's eyes are not blinded to the relatively low intensity of the 
neon receiving lamp. Kodak Abstr. Bull. 

Television in Colors by a Beam Scanning Method. H. E. IVES AND A. L. 
JOHNSRUD. /. Optical Soc. Amer., 20, January, 1930, p. 11. The positions of light 
source, image forming lens, and sensitive surface, with which we are familiar in 
photography, are revised. The lens projects a narrow moving beam of light, and 
the light reflected from the object is picked up by photo-electric cells which occupy 
the positions which in photography would be taken by the light sources. Three 
sets of special photo-electric cells are used, one with a green filter, one with a red 
filter, and one with a blue filter. The transmitted picture is produced by super- 



388 ABSTRACTS 

posing the light from three different colored television glow lamps by means of 
semi-transparent mirrors. The light source and the scanning disk are the same 
as those used for monochrome television. Kodak Abstr. Bull. 






BOOK REVIEWS 

Photocells and Their Application. V. K. ZWORYKIN AND E. D. WILSON. John 
Wiley & Sons, New York, N. Y., 1930, xi + 209 pp. (illustrated), $2.50. The 
authors have succeeded in their avowed attempt to present their material in a 
manner "not too technical for the untrained man nor too shallow for the special- 
ist." The untrained reader is lead by logical and natural steps to an understand- 
ing of photo-electric theory as he follows the historical development of the science 
through the experiments of Hertz, Hallwachs, Elster and Geitel, and Lenard. 
The inadequacy of classical physics to explain black body radiation and the 
release of electrons in the photo-emissive effect becomes apparent and thus the 
reader sees the necessity for quantum theory as proposed by Planck and applied 
by Einstein. 

Most of this first section is devoted to photo-emission though two chapters are 
devoted to photo-conductive and photo- voltaic effects. 

Commercial photo-cells, their manufacture, and characteristics are discussed in 
some detail and in a manner which should prove valuable to the research worker 
as well as to the less trained user. 

The use of the photo-cell in conjunction with thermionic tubes is described in 
the second half of the book. In this part also there appears to be a happy blending 
of the theoretical and the practical. Some of the applications which are treated 
are: sound motion pictures, facsimile transmission, television, relay devices, 
automatic inspection and control devices, and mechanical reading. While the 
description of these devices is not specific enough to enable "the amateur to build 
his own set," the details given do impart a fair amount of information as to the 
general principles involved. 

The authors have combed the literature for material to supplement their own 
broad experience in the field. Over one hundred references are cited and a com- 
prehensive bibliography is given. C. M. T. 



SOCIETY OF MOTION PICTURE 
ENGINEERS 

OFFICERS 

President 

J. I. CRABTREE, Eastman Kodak Co., Rochester, New York 

Past President 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

Vice-Presidents 

H. P. GAGE, Corning Glass Works, Corning, N. Y. 
K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 

Secretary 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

Treasurer 

W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

Board of Governors 

H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Roches- 
ter, N. Y. 

J. I. CRABTREE, Research Laboratory, Eastman Kodak Co., Roches- 
ter, N. Y. 

J. A. DUBRAY, Bell & Howell Co., 1801-1815 Larchmont Ave., Chi- 
cago, 111. 

H. P. GAGE, Corning Glass Works, Corning, N. Y. 

K. C. D. HICKMAN, Research Laboratory, Eastman Kodak Co., 
Rochester, N. Y. 

W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood 
Blvd., Los Angeles, Calif. 

P. MOLE, Mole-Richardson, Inc., 941 N. Sycamore Ave., Holly- 
wood, Calif. 

M. W. PALMER, Paramount-Famous-Lasky, Inc., 6th & Pierce Aves., 
Long Island City, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

S. ROWSON, Ideal Films, Ltd., 76 Wardour St., London, W. 1, England 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 
390 



391 



J. G. CAPSTAN 



J. W. COFFMAN 



E. ADAMS 

C. L. GREGORY 



J. W. COFFMAN 



C. BARRELL 
J. W. BOYLE 
W. H. CARSON 
W. CLARK 
L. W. DAVEE 



COMMITTEES 
1929-1930 

Color 

W. V. D. KELLEY, Chairman 

W. T. CRESPINBL F. K. IVBS 

Convention 

W. C. KUNZMANN, Chairman 

W. C. HUBBARD M. W. PALMER 

Historical Committee 

F. J. WILSTACH Chairman 

C. F. JENKINS A. S. NEWMAN 

O. NELSON T. RAMSAYE 

Journal 

L. A. JONES, Chairman 
H. T. COWLING W. C. HUBBARD 

J. H. KURLANDER 

Membership and Subscription 

H. T. COWLING, Chairman 

J. DEFRENES B. E. NORRISH 

E. R. GEIB I. ROSEMAN 

D. E. HYNDMAN E. C. SCHMITZ 

J. KLENKE J. L. SPENCE 

M. L. MISTRY F. ZUCKER 



Papers 

J. W. COFFMAN, Chairman 

M. C. BATSEL C. R. HANNA G. E. MATHER 

F. J. CADENAS K. C. D. HICKMAN R. F. NICHOLSON 

J. A. DUBRAY E. HUSE J. B. TAYLOR 

O. M. GLUNT D. E. HYNDMAN 



M. ABRIBAT 
J. A. BALL 

J. BOOLSKY 

W. CLARK 



Progress 

G. E. MATTHEWS, Chairman 

J. B. ENGL A. C. HARDY 

R. E. FARNHAM R. C. HUBBARD 

H. B. FRANKLIN G. F. RACKETT 

E. R. GEIB S. K. WOLF 
K. GEYER 



392 



COMMITTEES 



[J. S. M. p. E. 



H. W. DREYER 
G. C. EDWARDS 
P. H. EVANS 
T. FAULKNER 
J. H. GOLDBERG 



Projection 

L. M. TOWNSEND, Chairman 

C. GREENE R. MIEHLING 

H. GRIFFIN W. B. RAYTON 

N. M. LAPORTE F. H. RICHARDSON 
R. H. McCuLLOUGH H. B. SANTEE 



W. A. McNAiR 



D. F. WHITING 



K. C. BADGLEY 



Publicity 

W. WHITMORE, Chairman 
B. W. DEPUE 
G. E. MATTHEWS 
G. F. RACKETT 



O. A. Ross 



J. W. COFFMAN 



Solicitation 
E. P. CURTIS, Chairman 



E. A. WlLLIFORD 



Standards and Nomenclature 



M. C. BATSEL 
W. H. CARSON 
L. W. DAVEE 

A. DEBRIE 
L. DEFOREST 
J. A. DUBRAY 
E. W. ENG STROM 



A. C. HARDY, Chairman 
P. H. EVANS 
R. E. FARNHAM 
H. GRIFFIN 
R. C. HUBBARD 
L. A. JONES 
N. M. LAPORTE 
G. MITCHELL 
W. P. POWERS 



G. F. RACKETT 
W. B. RAYTON 
V. B. SEASE 
T. E. SHEA 
J. P. SPENCE 
E. I. SPONABLE 
L. T. TROLAND 



L. J. BUTTOLPH 



Studio Lighting 

A. C. DOWNES, Chairman 

R. E. FARNHAM M. W. PALMER 
K. C. D. HICKMAN 



J. C. AALBERG 
F. A. BENFORD 
A. C. DOWNES 



Theater Lighting 

C. E. EGELER, Chairman 
F. FALGE 
R. E. FARNHAM 



C. GREENE 
E. HUSE 
L. A. JONES 



Sept, 1930 j COMMITTEES 393 

CHICAGO SECTION 

J. A. DUBRAY, Chairman O. F. SPAHR, Manager 

J. E. JENKINS, Sec.-Treas. O. B. DEPuE, Manager 



LONDON SECTION 

SIMON ROWSON, Chairman 

A. NEWMAN, Vice- Chairman PAUL KIMBERLEY, Manager 
L. EVELEIGH, Secretary ALAN WILLIAMSON, Manager 

H. WOOD, Treasurer WILLIAM VINTEN, Manager 



NEW YORK SECTION 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 



PACIFIC COAST SECTION 

P. MOLE, Chairman C. DUNNING, Manager 

G. F. RACKETT, Sec.-Treas. E. HUSE, Manager 



REPORT FOR CONSIDERATION BY THE COMMITTEE 
ON LOCAL SECTIONS OF THE SOCIETY OF 
MOTION PICTURE ENGINEERS 

FOREWORD 

At a recent meeting of the Board I appointed a committee under 
the chairmanship of Dr. Hickman to report on the urgent problems 
which have arisen since local sections have been formed within the 
Society. 

It was desirable to have on this committee certain persons who were 
not able to attend a New York meeting and it follows that the busi- 
ness of the committee has been done largely by correspondence. The 
present interim report is as near an average as may be of the members' 
differing opinions. It was read at the Board meeting held in New York 
City on July 29th and was passed for publication in the JOURNAL. 

The report is published so that all persons interested may have an 
opportunity to comment either by mail or at the next convention. 
Guided by the consensus of opinion, the Board will then consider such 
modification of the by-laws as may be necessary to put the recom- 
mendations into effect. These clauses will be presented at the meet- 
ing and voted upon by the members. 

The prosperity of the Society depends so much on the harmonious 
relations of its sections that I cannot urge too strongly the careful 
reading of this report. Criticism and suggestions will be welcome and 
no constructive ideas will fail to find their place in the final report. 

J. I. CRABTREE, President 

COMMITTEE REPORT 

The members of the Society of Motion Picture Engineers who are 
scattered all over the world are sufficiently numerous in certain re- 
gions to make it profitable to have local meetings and to establish 
local sections of the Society. Sections have already been named in 
Chicago, Hollywood, London, and New York and certain problems 
have arisen in their management which make it necessary to ex- 
amine the whole question of their relations to one another and to the 
main body of the Society. 
394 



LOCAL SECTIONS 395 

The Purpose of the Society and Its Sections. The Society was 
started by a group of technical specialists for the purpose of collect- 
ing knowledge pertaining to motion pictures. Although the Society 
is supported by an industry which sells products competitively, it 
was realized that commercialism within the Society of Motion Pic- 
ture Engineers would hinder the spread of knowledge and detract 
from the authority of its scientific publications. The Society has 
maintained a standard of technical excellence and an aloofness from 
exploitation which is in keeping with the high tradition of other simi- 
lar engineering organizations. While such a policy preserved to the 
full, ability to collect and advance knowledge, it hindered the speed 
with which this information was made available to many desirable 
quarters. Consequently, the Society began to grow rapidly by the 
admission of many persons less scientifically qualified who needed in- 
formation for service work, or news or sales purposes. The Society 
has been proud of this extended influence but it must reaffirm em- 
phatically to these new good friends that its whole usefulness to them 
rests on its continued freedom from the least taint of political or com- 
mercial influence. 

The balance of power is so evenly distributed in the Society at large 
that there is little danger of a change of outlook. The local sections, 
however, cannot always be sure of an even admixture of technical 
and lay members and to these the warning must be sounded that the 
Society must be kept as wide open scientifically as it is closed com- 
mercially. The Society is careful to offer no degrees or obvious re- 
wards which would make it desirable for one commercial organization 
to seek membership and discourage membership for competitors. The 
Society is more in the position of a telephone exchange where useful- 
ness to one subscriber increases with each additional subscriber. 

The writers of this report cannot discourage too strongly the prac- 
tice of using the words "Member of the Society of Motion Picture 
Engineers" in displayed advertisements. If such an announcement 
is a useful distinction for certain persons in a locality it will discourage 
their inviting equally worthy competitors to form a section and thus 
defeat the fundamental purpose of the Society which is scientific 
cooperation. 

Allegiance. Members contributing to section activities sometimes 
find local responsibilities which are not always in direct accord with 
their responsibilities to the parent body. When such conflict occurs 
it must never be forgotten that there is only one Society of Motion 



396 LOCAL SECTIONS [j. s. M. p. E. 

Picture Engineers. The sub-groups have been brought into being by 
virtue of the previous existence of the parent body and they have 
inherited the organization, prestige, and benefits created by others 
than themselves. We must recognize as a fundamental axiom that 
any person joining the Society joins the whole Society and gives his 
allegiance to the whole Society first and to his section second. If 
it is found that, as a practical matter, loyalty to a section does, in 
fact, conflict with loyalty to the whole group the cause of this conflict 
must be studied by this committee and, if possible, removed. 

Eligibility for Local Membership. Any member of the Society of 
Motion Picture Engineers living in the prescribed area shall auto- 
matically be eligible for membership in that section. 

Membership of a section will confer benefits and entail responsi- 
bilities which will make it necessary for a national member to make 
voluntary application for local membership before he can be con- 
sidered officially enrolled. 

Although enrollment for local membership shall be voluntary, the 
Board of Managers of the section shall make it their business to notify 
all national members within the section limits of their eligibility to 
such membership. 

If a member wishes to disregard the local section he shall have the 
right to do so. 

The local section may not reject for membership any member in 
good standing in the Society. 

Scientific attainments and technical ability are the only criteria 
whereby an applicant may be judged. If these are found satisfactory 
by the Board of Governors, the local social, business, or political de- 
sirability of the applicant must not be allowed to interfere with the 
proper exercise of judgment. 

If, in the opinion of the Manager and Board of the local section, a 
member or an applicant is not a desirable person for their section 
they shall report their objection to the Board of Governors who may, 
at their discretion, remove his name from the Society's register or 
reject his application. 

The officers of the Board of Governors when deciding on an appli- 
cant's fitness for admission to the Society have in the absence of 
personal knowledge only two means of making a correct decision. 
They have the written record of the applicant's experience and they 
have the recommendation of his seconders. Both may contribute to 
a false decision. The Board charges the section managers to make 



Sept., 1930] LOCAL SECTIONS 397 

such full investigation into the record of the local applicant that a 
fair disposal of his case can be secured. 

Finances of Sections. During the past fourteen years the Treasurer 
and the Board of Governors have acquired a well defined knowledge 
of what is and what is not a proper expenditure of the Society's 
money. While some modification will be required to meet the needs 
of the sections, the underlying conception has proved too valuable to 
be abandoned. Proper expenditures have embraced primarily the 
printing of the JOURNAL, which has hitherto taken the largest por- 
tion of the funds, and the expenses of the Secretary's and Treasurer's 
offices. With the question of a paid secretary-treasurer or manager 
nearing its answer, it appears that the expenses of the JOURNAL and 
manager's office will rightly absorb nearly the whole of the Society's 
income. Other proper expenditures in the past have comprised 
clerical help for committees and items directly concerned with the 
furtherance of the Society's business. 

The purchase of food and entertainment, the hiring of lecture halls, 
payment to speakers, and other items of a like nature when considered 
desirable have generally been supported by special levies in the form 
of registration fees or banquet tickets. No difficulty has been en- 
countered in collecting these monies because members have recognized 
them as right and necessary additions to the annual dues. 

At present the main body of the Society has no headquarters and 
temporary headquarters are secured at the hotels when conventions 
are held. These premises, which nominally cost the Society nothing, 
are in reality paid for partly by the room rent of the convention dele- 
gates, and partly by the registration fees. The cost comes indirectly 
from the members in addition to their annual dues; and we may re- 
state this by saying that members pay a variable local subscription 
over and above their main contribution. This conclusion is of para- 
mount importance in the development of our argument. 

Local sections will desire, in general, to meet more frequently than 
the main body. The meetings will require headquarters, the use of 
projector apparatus, and in some cases the serving of refreshments. 
Board and entertainment for speakers, circularizing announcements 
of meetings, and perhaps publication of a local news letter may all 
be desirable. An annual dinner and other social functions will not be 
out of place. 

The executives of the Society have every sympathy with regional 
activities but the money for their entire support is not available. 



398 LOCAL SECTIONS [j. s. M. p. E. 

The JOURNAL costs over $8 per person and the clerical burden dis- 
tributed over the membership is $1.50 per head. Even when the 
sections are allowed as little as $2.00 a member for annual operating 
expenses it means that an associate member is being carried at a loss 
of $1.50. The active membership and the Society's more vicarious 
sources of income cover the deficiency and leave a small margin for 
the future establishment of New York national headquarters. 
Nothing that the parent body could ever contribute could defray 
the expenses of a really ambitious section. These funds must come 
out of the private pocket in the same way as the convention expenses 
of the parent body. 

Our established practice would suggest that in making up the 
annual budget the section should request the following appropriations: 

Premises and Apparatus A nominal amount 

Clerical work, membership campaign, reporting of 

lectures for use of Society, etc. Full cost 

Circularizing local members, printing of posters, 

tickets, news letter, etc. A nominal amount 

This budget should be supplemented by local levy for the following 
items: 

Premises and apparatus To remedy deficiency 

Circularizing local members, printing of posters, 

tickets, news letter To remedy deficiency 

Entertainment, food, and all local activities which 

do not concern the main body Full cost 

The possibility of making such collection equitably will be dis- 
cussed in the following paragraphs. 

Local Dues and Local Membership. It is not healthy for any or- 
ganization to be dependent in all its actions on a governing force situ- 
ated at a distance. Our sections should have a certain autonomy 
which will be the more productive the more it is complete. The 
Society is concerned with the progress of the motion picture art and 
is not interested in local manners or national prejudices. It is far 
more important that knowledge and standardization should spread 
throughout the world than that the branches of this Society, which 
will be instruments in this work, shall be forced to behave according 
to some pattern devised by and most nearly appropriate to one or 
another section. Indeed, it seems probable that the greatest co- 



Sept., 1930] LOCAL SECTIONS 399 

operation will go hand in hand with the greatest freedom in the 
manner of this cooperation. 

The two items in which freedom is most desired are: The control 
of money, and the control of personnel, yet we have previously sub- 
mitted that the Society has no money available for the uncontrolled 
local expenditure and also that the parent body must have the last 
word in the admission of members. 

We believe the solution of this paradox lies in the institution of 
local dues and local membership. 

There is excellent precedence for the subdivision of a large national 
or international society. The American Chemical Society, the Ameri- 
can Physical Society, and the American Optical Society go farther 
in this direction than need ever be considered for the S. M. P.-E. 
It allows its Rochester branch to have complete independence and 
adopt the title "Rochester Chemical Society" (Branch of the Ameri- 
can Chemical Society). The Rochester section levies a $2.00 annual 
subscription and elects all its officers locally. In contrast to this the 
American Institute of Electrical Engineers, the Institute of Radio 
Engineers, and the American Society of Mechanical Engineers have 
sub-groups in large cities which are treated according to the needs of 
the group. In some cases the section is a single gathering of national 
members in the locality and its limited finances are all contributed by 
the national body which remits to the local treasurer a certain pro- 
portion of each man's dues. In other cases the section is a flourishing 
local society, open to all suitable persons who pay local dues. They 
differ from the Rochester Chemical Society in that the name of the 
parent body is rigidly adopted for the local section. 

In the British Isles there are the Royal Societies of London, Edin- 
burgh, and Dublin, whose activities overlap because one society would 
not cover all the territory and cooperation of effort is not required. 
On the other hand, the London Chemical Society and the Institute 
of Chemistry which have been separate institutions for many years 
are now seeking common headquarters because they have a common 
program of technological development. The German Scientific 
Societies prefer regional colloquia. Universities arrange gatherings 
devoted to specified subjects which are attended by visitors from a 
distance. Conviviality merges with scientific discussion and the 
flow of rhetoric matches the flow of good German ale. The expense 
is not borne by the scientific society under whose aegis the meeting 
convenes. 



400 LOCAL SECTIONS [j. S. M. p. E. 

We see therefore in all parts of the world the splitting of national 
bodies and the consolidation of local bodies. When the former occurs 
local dues are generally instituted; when the latter takes place, the 
local subscription is already in existence. 

Let there be no misunderstanding about the question of local dues. 
It is not intended that the imposition of these should be compulsory. 
Where, for example, a rebate of $2.00 a head is considered sufficient 
for the conduct of local business it will be simpler to retain the present 
section structure. Where, on the other hand, local activities and 
ambitions find $2.00 totally inadequate the way should be made wide 
open to expand the section in finances and personnel as the local 
board sees fit. 

National members may look with some alarm on any proposal to 
increase their already substantial commitment to the Society by a 
local levy. This can be avoided by suitable technic. The local dues 
could be paid by local members alone, or in greater part by local 
members. For example, a group of 50 men receiving a rebate of 
$100 per annum from headquarters might be unable to make ends 
meet. A group of 50 national and 50 local members with a $500 
income made up of $5.00 dues for local members and $3.00 local dues 
plus $2.00 rebate for national members would form a powerful organi- 
zation. A $2.00 local membership requiring no subscription from 
national members might be instituted or a $5.00 local fee and still 
no national local fee would also be fair and possible. These are 
examples and are not intended to prejudice future local action. 

The structure which is now advocated for the Society of Motion 
Picture Engineers would contain any or all of the following variations: 

Members of the parent body paying full subscription and receiving all the 
benefits set out in the present constitution and by-laws. 

Members of the parent body paying full dues and registered (with or without 
extra dues as the case may be) as members of a local section, having full privileges 
and responsibilities of the Society and the section. 

Local members in those sections where local dues are imposed, such members to 
enjoy full local privileges and local voting power. 

Officers of sections must be elected by and themselves be active members of the 
parent body. 

Inclusion on demand after registration or the payment of local dues of any 
national member residing within the section limits. 

Admission at the discretion of the section committee of applicants for local 
membership for local dues only. 

Such a procedure puts into the hands of the sectional committee 



Sept., 1930] LOCAL SECTIONS 401 

two dearly cherished powers: firstly, the ability to develop, un- 
hampered, any plans which the locality feels inclined to support; 
and secondly, to extend the privileges of the branch to any person 
without let or hindrance. 

The objection to local membership has been voiced that many 
persons will be content to pay the smaller fee, reading the JOURNAL 
at the local headquarters rather than shouldering the full responsi- 
bilities of the Society. This contention is refuted by experience. Our 
national conventions are open to all comers; our JOURNAL can be 
bought for less than Active membership ; men who should pay Active 
fees can escape as Associates. Experience shows that advantage is 
seldom taken of these possibilities. A natural enthusiasm or at the 
worst a fear of public opinion makes each potential member an actual 
member. Sectional status in other societies has not furnished a cheap 
way out ; the sections have proved to be a recruiting ground for 
national members of more value than expensive membership drives 
waged from headquarters. 

Financial Procedure. At the present time one section collects 
the dues of the local members but in the case of the other three the 
treasurer of the main body transacts this business. The lack of 
uniformity is due to the fact that the one section is in a foreign 
country. The advantage of local collection for the British members 
is that it produces an intimacy of relationship between the officers 
and those members which might otherwise be absent. The disad- 
vantage is that delinquency, sometimes tolerated for local reasons, 
cannot be countenanced by the main body which has to pay for the 
printing of the JOURNAL. It is not always possible for the chief treas- 
urer to learn from the local treasurer exactly which members are 
entitled to receive the JOURNAL. 

We believe that with the establishment of local dues the business 
of collecting the main subscription should devolve in all cases on 
the Treasurer of the Board of Governors. If the treasurers of the 
sections wish to play some part in the collection they have scope for 
such activity in persuading delinquents to pay back dues and in 
forwarding application blanks and checks which they may secure 
personally from prospects. They will also be concerned without 
supervision with the collection of local dues. 

Boundaries of the American Sections. There are at least two well 
defined types of section limits. A section may be associated with a 
large town such as New York or Chicago and may by courtesy extend 



402 LOCAL SECTIONS [j. s. M. p. E 

membership to its suburbs or to a district with a radius of so many 
miles; or a section may comprise a region of country but still have 
headquarters in a large town. The former scheme will find the most 
enthusiastic support until it is realized that a number of national 
members will have no sectional facilities because they live between 
the section towns. Thus, Rochester which supports many Active 
members would be represented in neither New York or Chicago 
and Schenectady and Cleveland would be as unfortunate. We 
suggest that the limits divide the continent into three industrially 
equal portions with one division passing north and south 50 miles 
west of Cleveland, Ohio; while the other division passes north and 
south 50 miles west of Denver, Colorado. 

Out of Town Membership. Bearing in mind that the business 
of the Society is the spreading of knowledge, it should not be con- 
sidered improper to pass on descriptions of the activities of any 
one section to all in the Society who are interested. We propose, 
therefore, that any national member who cares to pay annually a 
sum less than the local subscription where such exists, as determined 
by the Board of Managers of a section, shall be placed on the mailing 
list to receive notices of lectures and all other literature which is 
circulated within the section. The payment of these out of town 
dues shall not permit the person to vote at meetings but shall entitle 
him to receive all other local benefits when visiting the sectional 
headquarters. 

SUMMARY 

The following recommendations are made: 

(1) It should be understood by all Active and Associate members 
that they are members of the main Society first and of a section 
second. 

(2) It is suggested that local membership shall be instituted. 

(3) The imposition of local dues is advocated. 

(4) Proper expenditures are defined. 

(5) Collection of dues for national membership should be from 
national headquarters. 

(6) Collection of local dues should be from local headquarters. 

(7) The American sections should divide the continent into three 
portions, the boundaries of which can be altered when new sections 
are formed. 



Sept., 1930] LOCAL SECTIONS 403 

(8) Any national member wishing to be informed of the activities 
of any section may be placed on the mailing list for sectional infor- 
mation upon payment of certain dues. This shall not entitle him 
to other local benefits, voting power, etc., unless he is a bona fide 
resident of the section. 

W. CLARK P. MOLE 

H. T. COWLING M. W. PALMER 

J. A. DUBRAY S. ROWSON 

W. C. HUBBARD K. C. HICKMAN, Chairman 



404 SOCIETY NOTES [J. S. M. p. B. 

SOCIETY NOTES 

The London Section. At a meeting of the Executive Committee 
held July 3rd, Mr. H. Wood resigned his position as treasurer and 
Mr. Paul Kimberley was appointed to carry on in his stead. The 
chairman on behalf of the whole Executive thanked Mr. Wood for 
what he had done on behalf of the Society. 

The resignation of Mr. Wood having created a vacancy in the 
Executive, the secretary was instructed to invite Dr. W. Clark to 
fill the vacancy until the next election. 

Board of Governors Meeting. At the meeting of the Board of 
Governors held at the Engineering Societies Building, New York, 
N. Y., Tuesday, July 29th, a large number of business matters were 
transacted, including the following: 

(1) Resolved that the fall meeting of the Society be held at the 
Pennsylvania Hotel, New York, N. Y., October 20th-23rd, inclusive. 

(2) Resolved that the name of "Hollywood" only be placed on 
the ballot for the location of the spring meeting. 

(3) Resolved that the geographical area of the Pacific Coast 
Section be defined as the territory of the United States lying west 
of a line running north and south through a point 50 miles west of 
Denver, Colorado; that the territorial area of the New York Section 
be bounded on the west by a line running north and south through 
a point 50 miles west of Cleveland, Ohio, and on the east by the 
Atlantic ocean ; that the Chicago Section include the territory which 
lies between the eastern boundary of the Pacific Coast Section and 
the western boundary of the New York Section. 

(4) A large number of matters relating to the London Section 
were discussed. To date there has been some misunderstanding 
with regard to the collection of membership dues. The treasurer 
of the parent Society had deputized the treasurer of the London 
Section to collect the dues, but owing to complications involved it 
has been agreed that the London Section forward dues in full di- 
rectly to the treasurer of the parent Society. Expenses of the 
London Section are to be defrayed only from the budgeted allowance 
in accordance with the By-Laws. 

(5) In order to more clearly define the relationship between the 
sections and the parent Society, especially with regard to finances, 
a committee was appointed under the chairmanship of Dr. Hickman 
to draw up a report. This was submitted to the Board of Governors 



Sept., 1930] SOCIETY NOTES 405 

and is published elsewhere in this issue of the JOURNAL. Every 
member is requested to carefully read over this report and submit 
any modifications or suggestions either to Dr. Hickman or the 
President. 

(6) A motion to reopen discussion on the matter of restoring the 
half -rate initiation fee to foreign members was defeated. It will be 
recalled that beginning October 1, 1930, the present half -rate mem- 
bership fee for foreign members will be raised to the same basis as 
that for residents of the United States and Canada. 

(7) Resolved that photographs of officers of the parent Society 
and sections be published annually in the JOURNAL. 

(8) The Secretary read a letter received from the Chairman of 
the Committee on Representation for the American Standards 
Association requesting the Society to take up membership. The 
Secretary was instructed to secure further information. 

(9) A committee consisting of Messrs. M. W. Palmer and J. H. 
Kurlander was empowered to rent office space in New York City at 
a price not to exceed $1500 per year when notified by the Secretary 
or President that the Society is ready to occupy such offices. 

(10) Nominations for the various retiring officers were balloted. 
The retiring officers are as follows: 

J. I. CRABTREE President 

H. P. GAGE Vice-President 

J. H. KURLANDER Secretary 

W. C. HUBBARD Treasurer 

H. T. COWLING 

TT7 ^ Governors 

W. C. KUNZMANN 

(11) Fifty-four applications for the position of editor-manager of 
the Society were considered and a list of selected applications referred 
to a committee consisting of Messrs. L. A. Jones, E. I. Sponable, 
and M. W. Palmer. The committee was instructed to interview 
applicants if necessary and report at the next Board meeting to be 
held September 22nd. 



406 OBITUARY [j. s. M. p. E. 

OBITUARY 

WILLIAM HENRY BRISTOL 

Mr. William H. Bristol, inventor, educator, and manufacturer, died 
on June 18, 1930, after a brief illness. His age at the time of his death 
was seventy- two years. 

Mr. Bristol was a leader in the engineering field. His inventions 
and developments of recording instruments, pressure gauges, pyrom- 
eters, and electrical measuring instruments have been of great 




PROF. W. H. BRISTOL 



service to many industries since he founded the Bristol Company at 
Waterbury, Connecticut, in 1899. 

He was a pioneer in the field of sound recording devices and for a 
number of years he has devoted a large part of his time to the de- 
velopment of sound motion pictures. 

His works are familiar to members of this Society through numer- 
ous papers which he has published in the Transactions and JOURNAL. 

He was a graduate from Stevens Institute with the degree of M.E. 
and was a member of a number of technical societies in addition to 
our own. 



Sept., 1930] 



NEW MEMBERS 



407 



NEW MEMBERS 
(May to August, 1930) 



ABGRALL, PIERRE J. (-4) 

Abgrall stablishmente, 16 Rue 

Roussel, Paris, XVII, France 
ANDERSON, ARTHUR H. (A) 

Duplex Motion Picture Industries, 
74 Sherman St., Long Island City, 
N. Y. 

BARBER, PERCIVAL A. (.4) 

52 Howbury Rd., New Head, Lon- 
don, S. E. 15, Eng. 
BAUER, KARL A. 04) 

Carl Zeiss, Inc., 485 Fifth Ave., New 

York, N. Y. 
BELL, CHARLES H. (M) 

166 Wardour St., London, W. 1, 

Eng. 
BRADFORD, ARTHUR J. (4) 

Visual Instruction Dept., General 

Electric Co., Schenectady, N. Y. 
BRADSHAW, DAVID Y. (A) 

2140 Champa St., Denver, Colo. 
BRAUER, ELMORE C. (A) 

407 llth St., Gothenburg, Neb. 
BURGESS, WILFRED E. (-4) 

P. O. Box 132, Stratford, New Zea- 
land 

CANTRELL, WALTER A. (A) 
23 Ogwen St., off West Derby Road, 

Liverpool, Eng. 
CHEFTEL, ALEXIS M. 04) 

22 Rue de Civry, Paris, XVI, 

France 

CHILTON, THOMAS (M) 
J. Frank Brockliss, Ltd., 58 Great 
Marlborough St., London, W. 1, 
Eng. 
CLAYTON, ROY S. (A) 

Metropolitan Sound Studios, Holly- 
wood, Calif. 
CRALLEY, VANE R. (-4) 
Metro-Goldwyn-Mayer Studios, 
Culver City, Calif. 



CRIST, RICHARD (A) 

6754 37th Ave., S. W., Seattle, Wash. 
CUNNINGHAM, JAMES B. (A) 

7023 Arcadia Ave., University City, 
Mo. 

DEROBERTS, RAYMOND (4) 

The Gevaert Co. of America, Inc., 
423 W. 55th St., New York, N. Y. 
DESAI, HARIBHAI (M) 
Surya Film Co., 5 Cunningham Rd., 
Bangalore City (Mysore State) 
India 

DOIRON, ALPHONSE L. 04) 
Metro-Goldwyn-Mayer Studios, Cul- 
ver City, Calif. 
DUFFEY, EDMUND J. (.4) 
The W. H. Hoedt Studios, 212 W. 
Washington Sq., Philadelphia, Pa. 

FALQUET, ALBERT 04) 

Kodak S. P. z. o. o., 5 Place Na- 
poleon, Warsaw, Poland 
FELSTEAD, CHARLES F. (.4) 

Universal Pictures Corp., Universal 

City, Calif. 
FENIMORE, ROGER W. (M) 

Chicago Film Lab., Inc., 1322 Bel- 

mont Ave., Chicago, 111. 
FRANK, JAMES, JR. (.4) 

RCA Photophone, Inc., 411 Fifth 
Ave., New York, N. Y. 

GEOGHEGAN, GERALDINE (M) 

The E. S. S. Colour Filter Co., 
1 Montague St., London, W. C. 1, 
Eng. 

GEYER, KARL H. (A) 
32 Wesbourne Terrace, London, W. 

2, Eng. 
GIBSON, GEORGE H. (A) 

J. E. Brulatour, Inc., 6700 Santa 
Monica Blvd., Hollywood, Calif. 



408 



NEW MEMBERS 



[j. s. M. p. E. 



GIHBSSON, LEIF (A) 

J. L. Nerlien, Ltd., Nedre slotsgate 

13, Oslo, Norway 
GLASSER, NAT (A) 

Warner Bros. Theatres, 923 F. St., 

N. W., Washington, D. C. 
GOLDEN, NATHAN D. (A) 

Motion Picture Division, U. S. Dept. 
of Commerce, Washington, D. C. 
GOLDBERG, JOE H. (M) 

Publix Theatres Corp., Room 1714, 
Paramount Bldg., New York, 
N. Y. 

HAEFELE, NORBERT C. (A) 

National Theatre Supply Co., 308 

Gay St., N., Baltimore, Md. 
HAUSER, FRANCIS V. 04) 

Stoll Picture Productions, Ltd., 
Temple Rd., Cricklewood, Lon- 
don, N. W. 2, Eng. 
HAWKER, CHARLES L. (A) 

Paramount-Famous-Lasky Studios 
5451 Marathon St., Hollywood, 
Calif. 
HEWITSON, ALAN E. 04) 

Messrs. Hewitsons, Ltd., Princes 
Hall, High St., Smethwick, Staffs., 
Eng. 
HOFFMAN, Louis B. (M) 

Blind Brook Lodge, Rye, N. Y. 
HORTON, JOSEPH W. 04) 

General Radio Co., 30 State St., 
Cambridge, Mass. 

INGMAN, THOMAS A. 04) 
Paramount-Famous-Lasky Lab., 1546 
N. Argyle Ave., Hollywood, 
Calif. 
IRBY, FRANKLIN S. 04) 

"Electronics," 36th St. and 10th 
Ave., New York, N. Y. 

JAY, RONALD L. 04) 

Jay's Screen Service, 23 Nithsdale 

Rd., Glasgow, S. 1, Scotland 
JOHN, WESLEY E. (4) 

National Bank Bldgs., Johannes- 
burg, South Africa 



KEITH, CLYDE R. (-4) 

Western Electric Co., Ltd., Inveresk 

House, Aldwych, London, Eng. 
KELLOG, EDWARD W. 04) 

RCA Victor Co., Inc., Camden, N. J. 
KOPPRASCH, ALEXANDER H. 04) 
Publix Theatres Corp., Room 1714, 
Paramount Bldg., New York, 
N. Y. 
KUMM, ARTHUR W. (A} 

Paramount - Famous - Lasky Corp., 
5451 Marathon St., Hollywood, 
Calif. 

LANSING, DUDLEY W. (A) 

RCA Photophone, Inc., 411 Fifth 

Ave.. New York, N. Y. 
LEWIS, GEORGE (M) 

Arcturus Radio Tube Co., 260 

Sherman Ave., Newark, N. J. 
LINSLEY, DOUGLAS F. 04) 

The Replitura Corp., Melrose Ave., 

Stamford, Conn. 
LONAS, FRANK E. 04) 

Woolworth Bldg., New York, N. Y. 
LUKES, STANLEY A. 04) 

6910 Greenview Ave., Rogers Park, 
Chicago, 111. 

MAC!LVAIN, KARL M. (M) 

3056 87th St., Jackson Heights, 

L. I., N. Y. 
MANLEY, R. G. H. (A) 

P. O. Box 772, Auckland, New Zea- 
land 
MARESCHAL, GEORGES (A) 

168 Rue de Belleville, Paris, 20e, 

France 
McCANN, FRANCIS D. (A) 

Westinghouse Electric & Manufac- 
turing Co., 150 Broadway, N. Y. 
MENEFEE, HARRY R. (M) 

Fox-Hearst Corp., 1776 Broadway, 

New York, N. Y. 
MESSTER, EDUARD O. (M) 

Messter Optikon G. m. b. H., Am 
Karlsbad 16, Berlin, W. 35, Ger- 
many 



Sept., 1930] 



NEW MEMBERS 



409 



MlKI, MlNORI (A} 

Makino Productions, Myoshinji 

Kyoto Shigai, Kyoto Perfecture, 

Japan 

MILLER, ARTHUR W. (A) 
47 Westfield Ave., E., Roselle Park, 

N.J. 
MILLER, JAMES A. (A) 

United Research Corp., 39th St. and 

Van Pelt Ave., Long Island City, 

N. Y. 

NEU, OSCAR F. (A) 

Neumade Products Corp., 442 W. 

42nd St., New York, N. Y. 
NIELSEN, JOHN F. (A) 

United Research Corp., 39th St. and 
Van Pelt Ave., Long Island City, 
N. Y. 

PEARSALL, EARLE S., JR. (M) 

Atlas Educational Film Co., 5 N. 

Wabash Ave., Chicago, 111. 
PECK, WILLIAM H. (M) 

Colorcraft Corp., 122 E. 42nd St., 
New York, N. Y. 

PlROVANO, LOUIS (A) 

Publix Theatres Corp., 60 Scollay 

Sq., Boston, Mass. 
Pu, MAUNG NYI (A) 

Burmese Favourite Co., 51 Sule 
Pagoda Rd., Rangoon, Burma 

REDFORD, CHARLES F. (A) 

Western Electric Co., Bush House, 
Aldwych, London, W. C. 2, Eng. 
RIDER, JOHN F. (M) 

1440 Broadway, New York, N. Y. 
ROMEO, GERARDO (A) 

31 rua Manuel Nobrega, Sao Paulo, 

Brazil 
ROPER, VAL J. (M) 

Eng. Dept., General Electric Co., 

Nela Park, Cleveland, Ohio 
ROSENSWEIG, MORRIS (A) 

H. E. R. Labs., Inc., 457 W. 46th 
St., New York, N. Y. 



ROSENMANN, GEORGE (A) 

Kodak S. P. z. o. o., 5 Place Na- 
poleon, Warsaw, Poland 

SAWADA, JUNSUKE (4) 

Sawada Productions, 25 Nishihagi- 
machi, Nishinariku, Osaka, Japan 
SILEN, HAROLD C. (M) 

Electrical Research Products, Inc., 
7046 Hollywood Blvd., Los An- 
geles, Calif. 
SCHICK, MARTIN C. (A) 

401 W. Washington Blvd., Fort 

Wayne, Ind. 
SCHMIDT, WILLY A. 04) 

Agfa Ansco Corp., Binghamton, 

N. Y. 
SCHOENBERG, VIRGIL A. (M) 

Enterprise Optical Mfg. Co., 564 W. 

Randolph St., Chicago, 111. 
SCHURMAN, FERDINAND (A) 

Fish Schurman Corp., 45 W. 45th 

St., New York, N. Y. 
SCHWARTZ, R. PLATO (M) 

University of Rochester, School of 
Medicine, Crittenden Blvd., 
Rochester, N. Y. 

THOMPSON, LINCOLN (M) 

Wm. H. Bristol Talking Pictures 

Corp., Waterbury, Conn. 
TILTZ, BERNARD E. (M) 

Tiltz Engineering Co., 480 Lexington 

Ave., New York, N. Y. 
TULPAN, SAMUEL (A) 

H. E. R. Labs., Inc., 457 W. 46th St., 
New York, N. Y. 

WALL, JOHN M. (M) 

J. M. Wall Machine Co., 101 Court 

St., Syracuse, N. Y. 
WALLACE, EDGAR B. (A) 

British Lion Film Co., Ltd., Lion 

Studios, Beaconsfield, Eng. 
WASCHNECK, KURT (M) 

Aktiengesellschaft fiir Film Fabrika- 
tion, Victoria strasse 13/18, Berlin- 
Tempelhof, Germany 



410 



UNKNOWN ADDRESSES 



[J. S. M. P. E- 



WHITE, RICHARD M. (A) 

Macoustic Engineering Co., Inc., 
Union Trust Bldg., Cleveland, 
Ohio 

WIENKE, EMIL J. (M) 

Enterprise Optical Mfg. Co., 564 W. 
Randolph St., Chicago, 111. 



WILLIAMS, R. GILLESPIE (M) 

Holophane, Ltd., Elverton St., Vin- 
cent Sq., London, S. W. 1, Eng. 



WILSON, JAMES (4) 

Gainsborough Studios, 
Islington, Eng. 



Poole St. 



YAGER, GEORGE A. (4) 

14 White Fawn Apts., Salt Lake 
City, Utah 

UNKNOWN ADDRESSES 

The present addresses of the following members are unknown to the Secretary. 
Information concerning their whereabouts should be sent to Mr. J. H. Kurlander, 
2 Clearfield Ave., Bloomfield, N. J. 



BLINN, ARTHUR F. 

Hollywood, Calif. 
BURGESS, FRANCIS J. 

Hollywood, Calif. 
CAUDE, ERNESTO 

Rome, Italy 



GREENE, EDWARD J. 

Chicago, 111. 
SMITH, J. C. 

Hollywood, Calif. 
ZERK, OSCAR U. 

Chicago, 111. 



Sept., 1930] 



411 



SUSTAINING MEMBERS 

Agfa Ansco Corporation 

Audio-Cinema, Inc. 
Bausch & Lomb Optical Co. 

Bell & Howell Co. 
Bell Telephone Laboratories, Inc. 

Case Research Laboratory 

Consolidated Film Industries 

DuPont-Pathe Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theatres Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Pacent Reproducer Corp. 

Paramount-Famous-Lasky Corp. 

RCA Photophone, Inc. 
Technicolor Motion Picture Corp. 



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JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 
Volume XV OCTOBER, 1930 Number 4 

CONTENTS 

Page 
Factors Governing Power Capacity of Sound Reproducing 

Equipment in Theaters. . .S. K. WOLF AND W. J. SETTE 415 

Galvanometers for Variable Area Recording. .G. L. DIMMICK 428 

Progress in Micro Cinematography .... HEINZ ROSENBERGER 439 

Television Systems .C. FRANCIS JENKINS 445 

Modern Practice in Incandescent Cinema Studio Lighting. . . . 

W. A. VILLIERS 451 

One Type of Acoustic Distortion in Sound Picture Sets 

R. L. HANSON 460 
Production Aspects of a Technical Lecture Sound Picture. . . . 

FRANKLIN L. HUNT 473 
Some Considerations Affecting the Design of Phonograph 

Needles R. T. FRIEBUS 484 

Improved Synchronizing Apparatus for Sixteen Millimeter 

Films with Disk Records WILLIAM H. BRISTOL 494 

The Maintenance of Sound Film in Exchange Operation and the 
Degree That Sound Reproduction Is Affected by the Con- 
tinued Use of Sound Track Film. .. .TREVOR FAULKNER 501 

The Soviet Cinematography L. I. MONOSSON 509 

Conditions under Which Residual Sound in Reverberant 

Rooms May Have More Than One Rate of Decay 

CARL F. EYRING 528 

Report of Projection and Sound Reproduction Committee 550 

Abstracts 565 

Book Reviews 570 

Officers 571 

Committees 572 

Society Notes 575 

Obituary 581 



JOURNAL 

OF THE SOCIETY OF 

MOTION PICTURE ENGINEERS 

LOYD A. JONES, EDITOR pro tern. 

Associate Editors 

G. L. CHANIER P. MOLE S. E. SHEPPARD 

O. M. GLUNT W. B. RAYTON J. L. SPENCE 

A. C. HARDY P. E. SABINE L. T. TROLAND 



Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
Editorial Office, 343 State St., Rochester, N. Y. 



Copyrighted, 1930, by the Society of Motion Picture Engineers 



Subscription to non-members $12.00 per year; single copies $1.50. Order from 
the Secretary of the Society of Motion Picture Engineers, 20th and Northampton 
Sts., Easton, Pa., or 2 Clearfield Ave., Bloomfield, N. J. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Application pending for second-class entry at the Post Office at Easton, Pa 



FACTORS GOVERNING POWER CAPACITY OF SOUND 
REPRODUCING EQUIPMENT IN THEATERS 

S. K. WOLF AND W. J. SETTE* 

GENERAL 

Reproduction of speech and music with motion pictures is intended 
to augment enjoyment derived by theater audiences. Of the factors 
which contribute to ease and pleasure of listening to reproduced 
sound, the quantity (loudness) of sound available to listeners ranks 
in importance with the quality of reproduction. Quality is of little 
avail when satisfactory loudness does not accompany it, and increase 
of loudness cannot compensate for quality that is poor. Sensation 
level influences intelligibility and naturalness of speech and music 
and, therefore, must be considered an important element in the 
promotion of satisfaction with sound picture presentation in theaters. 

It is the purpose of this paper to analyze the factors governing 
the power capacity of reproducing systems necessary to produce 
satisfactory loudness in auditoriums. The investigation readily 
resolves itself into a determination of the aural and auditorium 
factors bearing on listening conditions, a study of the characteristics 
of amplifiers, and the correlation of theaters and equipment to attain 
optimum audition. The limits for power capacity of reproducing 
apparatus which it is practicable to install in theaters with satis- 
factory results can thus be discussed, and existing limits examined 
in the light of these considerations. 

LISTENING LEVELS 

The first step appears to be to fix the desirable sensation levels for 
listening to speech and music. Ordinary conversation is heard at a 
level of about 70 decibels above threshold of audibility, for the 
stronger speech sounds, 50 decibels for weak sibilants. 1 In other 
words, vowel sounds thus spoken are ten million times as powerful 
as when just audible. This intensity is such that words are heard 

* Electrical Research Products, Inc., New York City. (Read before the New 
York Section.) 

415 



416 S. K. WOLF AND W. J. SETTE [j. s. M. P. E. 

at maximum intelligibility, greater or less intensity both tending 
to reduce intelligibility. Accordingly in the theater this level may 
be considered comfortable from the standpoint of articulation and 
naturalness. However, other phenomena must be taken into account. 
Noises due to audience, ventilating equipment, and external 
sources, ranging from 10 to 40 decibels above threshold, may be pres- 
ent, requiring increase in loudness of speech for good articulation. 
If we engineer on the basis of a recorded intensity range of 40 deci- 
bels, which represents exceptional recording, and if the minimum 
reproduced sound is made equal to the maximum room noise, it will 
be evident that the maximum sensation level will be 80 decibels 
instead of 70. 2 The excess level of 10 decibels would seem a reasonable 
reserve since speech at a level of 70 decibels is readily intelligible 
in the presence of an ordinary amount of room noise. In connection 
with this it must be remembered that it is more desirable to reduce 
noise than to increase the level of reproduction. In regard to music 
there is little data available as to natural levels for listening. We 
may fix the maximum average level which reproducing equipment 
will be required to produce in a theater as in the neighborhood 
of 80 decibels, selecting this figure in view of the fact that the mea- 
sured outputs of musical instruments are generally higher than those 
for the average speaker. This selection is arbitrary, of course, and 
will provide for possible variation in different types of speech as well 
as music. The level of 80 decibels corresponds to a flux of 10 ~ 2 
microwatts of acoustic power per square centimeter. 

CHARACTERISTICS OF AMPLIFIERS 

The amount of power available from sound reproduction equip- 
ment will depend on the amplifiers incorporated into the apparatus 
and efficiency of loud speakers. We must determine the maximum 
average power without distortion in quality. The distortion in 
which we are interested in this discussion is caused by requiring 
amplifiers to work at overload conditions and is evidenced by a 
certain fuzziness and rattle in the reproduced sounds. Overload 
has the effect of introducing frequencies which may not be contained 
in the input or, in other words, producing nonlinear amplification 
of the signals. 3 The effect is to be avoided as it reduces articulation 
and naturalness of speech and tends to destroy quality of music, 
the degradation in quality being dependent upon the frequency 
distribution or spectrum of the extraneous sounds. 4 We conclude 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 



417 



that amplifying equipment should be designed to be capable of 
producing necessary power without encroaching on the nonlinear 
part of the amplification curve. 

There are several practiced methods of rating amplifiers. Those 
made by the Western Electric Company are rated by their electric 
output at 1000 cycles as this frequency lies approximately in the 
middle of their pitch range and has been found to be a very useful 
reference frequency. With this method overload is said to occur 
when the added third harmonic is greater than 1 per cent of the power 
of the pure sine wave fundamental, in the output. It remains for 



! 

L 

I- 

Cfc 1.0 

! 



10 



zo 



30 



SO 



60 



70 



80 



/OO 



CUBE ROOT 0/= YOLVME /=EET 

FIG. 1. Optimum reverberation time and cube root of auditorium volume. 



us to translate this rated power of the equipment into something 
which we can compare with figures for speech powers. 5 The average 
for continuous speech over a long period has been determined as 10 
microwatts for the average speaker. The instantaneous peak values 
may rise to 200 times that amount. Thus an accented syllable like 
"tap" will frequently be distorted in reproduction because the 
instantaneous power involved is greater than for most syllables. 
We are interested in a rating comparable to the sensation level of 70 
decibels considered optimum from the standpoint of articulation, 



418 



S. K. WOLF AND W. J. SETTE 



[J. S. M. P. E. 



In amplification it is the peak portions of the signals that are 
distorted at overload. Thus the tops of sine waves may be flattened. 
If we assume that the peaks of speech will be distorted in similar 
fashion, we may set a value for speech output relative to the single 
frequency. For vowel sounds the instantaneous power reaches 20 
times the syllabic. The latter would, therefore, be some 13 decibels 
less than the peak undistorted power. Since the peak of a sine wave 
is 3 decibels above the average in power, then the rating for speech 
should be in the neighborhood of 10 decibels less than that given for 



JO 



.OS 



/oooo 



200OO 



30000 



40000 



soooo 



FIG. 2. Acoustic power for sensation level of 80 db. as a function of 

absorption. 



the single frequency. This output is that which may be used in 
sensation level calculations. Computation of the rating in this 
manner is not entirely justifiable since audibility of distortion must 
be weighed. However, in practice it has been usually found safe 
to allow a difference of 5 decibels between the maximum average 
power of both speech and music and the single frequency rating for 
high quality amplification. More elaborate experimental work 
should be done before positive statements in this connection are 
made. 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 419 

LOUD SPEAKERS 

The electrical energy furnished by the amplifying apparatus must 
be converted into acoustic energy. The efficiency of this trans- 
formation depends on the type of loud speaker that is employed. 
With exponential horns equipped with receivers like the W.E. 555, 
efficiencies as high as 25 per cent are realized. 6 Thus an attenuation 
of 6 decibels is introduced in going from the electric to acoustic power. 
If the horns are placed behind the screen in a theater, power may be 
lost in transmission and by reflection. The amount varies with the 
material, porosity, and location relative to the screen, being approxi- 
mately 1 or 2 decibels in tests for some screens and up to 5 decibels 
at 5000 cycles for poorer ones. 7 

We may summarize here and write down the acoustic power 
actually available for distribution into an auditorium. From the 
above considerations the maximum average speech power is about 
13 decibels down from the single frequency electric rating for re- 
producing equipment installed in a theater. Thus a system whose 
electric capacity is given as 5 watts could produce 250 milliwatts of 
acoustic power, 25,000 times as great as the value for average speech. 

DISTRIBUTION 

Most loud speakers are directional in their distribution of energy. 
Horn type speakers exhibit this property to a marked degree, the 
usual baffle type speakers to a less extent. 8 This property appears 
to be a rather desirable one in theater work as it enables placement 
of sound energy where it will do the most good. It serves as a tool 
in meeting the problem of distribution in large auditoriums since 
much reverberation cannot be utilized without loss of intelligibility. 
However, care must be exercised to see that some areas are not 
sacrificed because of too great intensities on the axes of the horns. 
This may be illustrated by assuming three areas of 1 square foot 
each with sound at a sensation level of 80 decibels over all of them. 
If, through faulty distribution, one of the square feet were increased 
to a level of 83, both of the remaining two unit areas would be cor- 
respondingly reduced to 77 decibels. 

AUDITORIUM FACTORS 

Auditorium factors must next be considered. It remains to calcu- 
late the power required to produce adequate levels of sound in- 
tensity throughout a theater. This power should depend in some way 



420 S. K. WOLF AND W. J. SETTE [j. s. M. P. E. 

on the volume and shape of a theater, the seating area, and the acous- 
tic absorption of the surfaces. The absorption present and the con- 
figuration determine the influence of reflected energy; the seating 
area is the surface over which satisfactory conditions are desired. 
It might be expected that with all these variables weighted, the 
required power, in general, will increase with the cubical content; 
that is, the power should be expressible as a function of the volume, 
perhaps a constant times the volume to an exponent less than unity. 
Ordinary reverberation theory, assuming a uniform distribution 
of acoustic energy, leads to the following relation between the equilib- 
rium condition of sound energy in a room and the source of con- 
stant output: 

- ...................... <> 



in which e Average energy per unit volume at steady state 
E = Acoustic power of source 
A = Total acoustic absorption of room 
C = Velocity of sound, 

where in words the formula states that if we measured the over-all 
average energy in an enclosed space, we would find it to be directly 
proportional to the power of the source and inversely proportional 
to the absorption in the space. Knowing the energy density through- 
out the room it is possible to calculate the sensation level of the sound. 
In decibels above threshold this is just 10 times the logarithm of 
the ratio of the maintained energy to the energy at zero audibility: 

47? / 
L- lOlogio T .................. (2) 

i = energy density at threshold. 

From this formula it appears that, if equal conditions of loudness 
are desired in all theaters, the necessary power should vary directly 
as the acoustic absorption present. Thus, a theater having 10,000 
units of absorption (corresponding to a volume of about 280,000 
cu. ft.) would require a sound reproduction system having twice the 
capacity of one that was adequate for a house with only 5000 units 
of absorption (120,000 cu. ft.). Another angle is that, on the basis 
of this theory, the same equipment installed in these two houses 
would create hearing levels differing by only 3 decibels, a difference 
which is little more than just distinguishable to the ordinary ear, 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 



421 



Attempts have been made to make the optimum absorption for 
theaters the yardstick for power capacity of reproducing equipment 
possible to install with satisfactory results. From the relation 
between optimum reverberation time and volume of auditorium 
it is possible to compute a curve connecting volume and most de- 
sjrable amount of absorption. Hence, curves 1 to 3 may be calcu- 
lated to show a theoretical relation connecting powers to produce a 
level of 80 decibels in auditoriums of different volume, assuming 
optimum absorption. 9 From the curves, and what we have already 



/KOUST/C PO we# //v DEC/B^L s 

N. 












































30 








































































































































































20 








































































































































































10 




























/" 


































^ 


^ 


X 


^ 
































^ 


^ 






































^^ 





































x 1 


X 


"' 






























0+ 


/0 s 


/o e /o 



VOLUME /A/ CUBtC FT 

FIG. 3. Acoustic power in decibels above 0.006 watt as a function of 
volume assuming optimum absorption. 



reviewed concerning amplifiers, limits for size of theaters and ca- 
pacity of reproducing equipment could be established. 

Fig. 3 shows the required acoustic power in decibels about 0.006 
watt plotted against a logarithmic scale of volume. The variables 
are considered logarithmically since loudness and sensation level are 
logarithmic functions of acoustic power. It is apparent that over 
the limited range in which we are interested the equation rather 
exactly expressing the graphed relation is: 



P db . = 8.1 log 7 - 38.2, 



(3) 



422 



S. K. WOLF AND W. J. SETTE 



[J. S. M. P. E. 



The value of 8.1, as the slope, indicates that the power in watts will 
increase as V to the 0.81 power. Corresponding to this logarithmic 
expression is the following for the acoustic power in microwatts: 

P = 0.91 V ' 81 (4) 

From what we have previously established, it follows that the elec- 
trical must be about 8 decibels above, and the amplifier singfe 
frequency capacity some 13 decibels above its acoustic power. 



16000 



/20OO 



6000 



4000 



5000 



/OOOO 



2OOOO 



2SOOO 



SQU#/Z reer 

FIG. 4. Relation between area occupied by audience and auditorium 
volume to the two-thirds power. 



The premises of the theory leading to the above equation should 
be examined to obtain an accurate estimate of the conclusions re- 
ported in the preceding paragraph. The formula 



e = 



4E 
GA 



expresses the average conditions existing when a sound source 
of constant power is in equilibrium with the absorption of energy 
at the surfaces enclosing a room. The average is to be understood 
as the total energy in the enclosed space divided by the volume. 
The condition of equilibrium means that a steady state must be 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 



423 



reached before the equation holds true. It can be shown that the 
time necessary for conditions to approximate the steady state is 
something greater than 0.3 second for most theaters. In speech 
the consonant portions of the syllables require only about 0.05 
second for enunciation, the vowel sounds about 0.2 second. There- 
fore, application of the equation to obtain loudness produced by 
speech sounds is open to doubt as the times dealt with are rather too 
short for the assumptions to apply in all but the smallest volumes. 
Furthermore, the theory assumes random distribution ; it is desirable 



20 



fO 



/0* /0 s 

VOLUME /N CUB/C 

FIG. 5. Acoustic power in decibels above 0.006 watt as a function of 
volume on the basis of seating area. 



to have sound reach the audience directly from the screen if illusion 
is to be maintained. Calculations have been made showing that 
loudness at points in an auditorium is affected less than 5 decibels 
by helpful reflections, that the impression of loudness is obtained 
mostly from direct energy, especially with directional sources such 
as horn speakers. 10 Accordingly the absorption present cannot 
be entirely indicative of sensation level. 

The formula obviously breaks down in the limiting case of open 
air theaters, or in enclosures where the surfaces are nearly 100 
per cent absorbent as here the inverse square of distance relation 



424 S. K. WOLF AND W. J. SETTE [J. S. M. P. E. 

applies. As wall surfaces are made more absorbing, the assumptions 
necessary for the derivation of the formula are less applicable. 
Several writers have advocated acoustically "dead" auditoriums. 11 
In this event, loudness, and consequently amplifier output to produce 
it, must be figured on some other basis as we shall see in the next 
section. 

If we do not accept the absorption theory as a criterion, there 
remains little basis for a computation of the required acoustic power. 
However, another starting point for the theoretical calculation 
would be the area occupied by an audience and presented to the horn 
to be covered. Thus, if uniform distribution could be achieved, 
a reproducing system with an acoustic capacity of 50 milliwatts could 
produce a sensation level of 80 decibels over an area of 5400 sq. ft. 
neglecting any aid from reflection. The same system with proper 
distribution would produce a level of 77 decibels over twice the area, 
10,800 sq. ft. But, obviously, area alone cannot be made the sole 
factor; the distribution must be uniform and effective. Accordingly, 
it would be better to speak of "effective area" rather than "area" 
where the term "effective" should weight the efficiency of direct 
covering and any aid from reflection. 

We may assume that effective area will be proportional to the 
seating area and hence vary in some manner as the volume of theaters. 
Fig. 4 represents the variation of seating area, including aisles and 
crosswalks, with volume to the two-thirds power. The relation is 
suggested by the geometrical consideration that on an average the 
surface of enclosures increases according to the square of the cube 
root of the volume. Of course, over a large number of theaters 
there will be considerable deviation from the values indicated by the 
curve, but a general average is of interest and serves our purpose. 
The equation connecting volume and seating area is: 

S = 2.56 V s/t (5) 

If we assume that aid by reflection just compensates for the in- 
crease of power that would be needed because of faulty distribution, 
then the effective area will be equal to the audience area. The 
acoustic power in microwatts required to produce sensation level 
o^ SO decibels in an auditorium would be, therefore, 

P = 23.8 F 2/3 (V in cu, ft.) , . (6) 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 



425 



The acoustic power in decibels referred to 6 milliwatts as a zero level 
is shown in Fig. 5. The relation is: 

p db = 0.7 log V - 24 (7) 

The exponent of the volume here, 0.67, compares with the value of 
0.81 obtained on the premise that the optimum absorption should 
govern the required power. 

EMPIRICAL RESULTS 

Our theoretical considerations involve assumptions which leave 
conclusions based on them open to doubt. They offer no conclusive 



















































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90 














































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80 


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70 


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YOLUM /N CU8/C FET 

FIG. 6. Acoustic power in decibels above 0.006 watt as a function of 
volume from experimental data. 

relation for fixing limits of amplifier capacity for auditoriums. 
Empirical results in this connection are of interest. Fig. 6 shows 
curves computed from data on public address systems collected by 
D. G. Blattner and J. P. Maxfield. Measurements were made by 
several observers of the electric power into the loud speakers at 
optimum audition in auditoriums of different sizes. The results 
indicate that the required power increased according to the volume 
to some exponent of the order of 0.71. The lower curve in the figure 



426 



S. K. WOLF AND W. J. SETTE 



[J. S. M. p. E. 



shows the relation with the electric converted to acoustic power. 
Because of the manner of making the adjustments, the sensation 
level produced should correspond to that considered satisfactory 
for ordinary speech reception in the previous sections of this paper, 
70 decibels above hearing threshold. The upper curve, elevated 
10 decibels from the observed one, corresponds to the level of 80 
decibels already mentioned, and is intended to demonstrate the 
power required for music and fluctuations in dramatic speech. In 
the theater provision is made for reserve amplifier capacity for large 



20 



IO 



4Bso/?f>r/ori 

2. 0GEA 

3. 



VOLUME IN CUB/C 

FIG. 7. Comparison of acoustic powers calculated for sensation level of 80 db. 

musical numbers, explosions, wrecks, etc. The equation for the 
upper curve is 

P db , = 7.1 log V - 27.7 (8) 

The power in microwatts is given by 

P = 10.2 F- 71 (9) 

DISCUSSION OF RESULTS 

Fig. 7 shows the three curves for the required power for an 80 
decibel sensation level, calculated from the optimum absorption, 
from the seating area, and from the actual observations. The load 
carrying capacity of amplifiers must be taken as some 13 decibels 



Oct., 1930] FACTORS GOVERNING SOUND EQUIPMENT 427 

higher than the acoustic power given here. The empirical curve 
lies between the others, as might be expected, with the seating area 
curve representing the better approximation to it. The value of 
the slope, 7.1, which may be considered of more interest than the 
actual magnitudes of the power, is also nearer in about the same 
proportion to 6.7, the slope of the upper curve, than to 8.1. This 
seems to check our view that absorption in theaters cannot be the 
correct criterion for computation of power, while it is a factor of some 
importance. 

The agreement among these curves is surprising and should be 
regarded as substantiating but not final evidence of the correctness 
of our conclusions. There are involved too many variables which 
are impossible of sufficiently exact estimation. The results may be 
used to forecast requirements in most new instances. In practice 
some deviation due to differing structure of theaters and efficiency 
of distribution of sound is to be expected as we have attempted to 
deal with averages here. 

REFERENCES 

1 FLETCHER, H. : "Speech and Hearing," 1st ed. D, Van Nostrand, New York 
(1929), p. 272. 

2 MACKENZIE, D.: "Motion Picture Sound Recording," Acad. Tech. Digest, 
Acad. of M. P. Arts and Sciences, Hollywood, Cal. (1929), p. 133. 

3 WILLIS, F. C., AND MELHUISH, L. E.: "Load Carrying Capacity of Ampli- 
fiers," Bell Syst. Tech. J., V (1926), No. 4, p. 573. 

4 STEINBERG, J. C.: "Effects of Distortion upon the Recognition of Speech 
Sounds," /. Acoustical Soc. Amer., 1 (1929), No. 1, p. 121. 

5 SACIA, C. F.: "Speech and Power Energy," Bell Syst. Tech. J.. IV 
(1925), No. 4, p. 627. SACIA, C. F., AND BECK, C. J.: "The Power of Funda- 
mental Speech Sounds," Bell Syst. Tech. J., V (1926), No. 3, p. 463. 

WENTE, E. C., AND THURAS, A. L.: "High Efficiency Receiver of Large 
Power Capacity," Bell. Syst. Tech. J., VII (1928), No. 1, p. 140. 

7 HOPKINS, H. F.: "Considerations in the Design and Testing of Motion 
Picture Screens for Sound Picture Work," /. Soc. Mot. Pict. Eng., XV (1930), No. 
3, p. 320. 

8 BLATTNER, D. G., AND BOSTWICK, L. G.: "Loud Speakers for Use in 
Theaters," /. Soc. Mot. Pict. Eng., XIV (1930), No. 2, p. 161. 

9 WOLF, S. K.: "Theater Acoustics for Sound Reproduction," /. Soc. Mot. 
Pict. Eng., XIV (1930), No. 2, p. 151. 

10 PETZOLD, E.: "Elementare Raum Akustik," 1st ed. Bauwelt-Verlag, 
Berlin (1927), p. 74. 

11 KELLOGG, E. W.: "Some New Aspects of Reverberation," /. Soc. Mot. 
Pict. Eng., XIV (1930), No. 1, p. 96. WATSON, F. R.: "Acoustics of Buildings," 
2nd ed. John Wiley and Sons, New York (1930), p. 58. 



GALVANOMETERS FOR VARIABLE AREA RECORDING 

G. L. DIMMICK* 

In the process of recording sound on film by the variable area method, 
it is necessary to modulate a narrow beam of light in such manner 
that its length at any instant is directly proportional to the sound 
pressure on a microphone diaphragm. This result has been success- 
fully accomplished in four steps as follows: (1) A microphone 
converts the sound energy into electrical energy. (2) An amplifier 
makes it possible for the microphone to control a relatively large 
amount of electrical energy. (3) A galvanometer converts this 
electrical energy into mechanical energy in the form of rotational 
vibrations of a small mirror. (4) An optical system enables the 
mirror to control the length of a small beam of light which is focused 
upon the film. This paper is concerned with a description of several 
types of galvanometers used in this process and a discussion of factors 
in their design. 

A method of coupling the vibrating mirror to the recording light 
beam is shown in Fig. 1. The filament of an incandescent lamp, 1, 
is focused upon a small galvanometer mirror, 5, by means of a con- 
denser lens, 2. In the horizontal plane the light stop, 3, is focused 
upon a narrow slit, 8, by means of lens, 4. In the same plane, lens, 
7, produces an image of the mirror, 5, at the objective lens, 9. 
In the vertical plane the mirror is focused upon slit, 8, by the cy- 
lindrical lens, 6. The objective lens forms an image of the slit upon 
the film. Under normal conditions, one-half of the slit is covered 
with light, and the other half is dark. If the galvanometer mirror 
executes rotational vibrations, the light beam vibrates linearly 
across the slit, thereby changing the length of the illuminated image 
at the film. 

If the galvanometer is to introduce negligible distortion into a 
sound record, it should meet certain definite requirements as to its 
characteristics. A linear relation should exist between mirror de- 

* Radio Victor Corp., Camden, N. J. (Read before the Society at Washing- 
ton.) 
428 



GALVANOMETERS FOR RECORDING 



420 



flection and applied voltage, within the working range. The am- 
plitude of the mirror deflection for a constant applied voltage 
should be substantially constant throughout the audio frequency 
range. No appreciable change in the phase relation of various fre- 
quencies should be introduced by the galvanometer. It is im- 
possible with any type of vibrating mechanical system to exactly 
meet these requirements. The principal factors upon which dis- 
tortion depends and the degree to which it can be eliminated appear 
from a brief analysis of the equations of a rotational vibrating system. 




FIG. 1. Optical system for variable area recording. 



The vector equation of such a system containing mass, stiffness, and 
resistance is 

T m 



(s -mw 2 ) + j rw" 

where Q m is the maximum angular displacement, T m is the maximum 
value of applied torque, 5 is the elastic restoring moment, r is the 
moment due to resistance, m is the moment of inertia, and w is 2r 
times the frequency. The phase angle between displacement and 
applied torque is 



tan' 



rw 



(2) 



The interpretation of these equations is somewhat simplified by 



430 



G. L. DlMMICK 



[J. S. M. P. E. 



substituting for m its equivalent s/w\ where W Q is the value of w 
at resonance. Also the fraction W/WQ is replaced by u and r WQ/S 
is replaced by B. Equations (1) and (2) then take the form 



and 



*[(! - uY +jBu] 
Bu 



a = tan 



(3) 



(4) 



I - u 2 " 
where B, which is called the bluntness, is the ratio of maximum 




FIG. 2. Response curves for a damped vibrating mechanical system. 

deflection at low frequencies to that at resonance, and u is the ratio 
of w at any frequency to its value at resonance. From equation 
(3) it is seen that 6 m at low frequencies is equal to T m /s. If we let 
R be the ratio of galvanometer response at any frequency to its 
response at low frequencies then 



Oct., 1930] 



GALVANOMETERS FOR RECORDING 



431 



R = 



1 



(1 - w 2 ) +jBu 



In Fig. 2 is a family of curves plotted from equation (5). These 
curves show that if the galvanometer is too heavily damped, that 
is, B = 2 or more, high frequencies will not receive proper emphasis 
in the sound record. Underdamping, B = 0.5 or less, results in an 
exaggeration of the frequencies near resonance. A galvanometer 
which is damped to a bluntness of one produces very little amplitude 
distortion between the frequency limits of zero and resonance. 




FIG. 3. Curves showing the phase shift produced by a damped 
vibrating mechanical system. 



Within a given frequency range, it is possible to make the amplitude 
distortion entirely negligible by so designing the vibrating system 
that resonance occurs at a much higher frequency than it is desired 
to record. The efficiency of such a system would, however, be poor 
since the power required at low frequencies for a given angular 
deflection is proportional to the fourth power of the resonance 
frequency. The best condition for high efficiency and minimum 
distortion is obtained when resonance occurs at a frequency slightly 



432 



. L. DlMMICK 



\J. S. M. P. 



lower than the maximum which it is desired to record and the blunt- 
ness is approximately one. 

In Fig. 3 is shown a family of curves plotted from equation (4). 
These curves show the relationship between phase shift due to the 
galvanometer and the fraction W/WQ. An inspection of these curves 
shows that at resonance a phase shift of 90 degrees occurs regardless 
of the amount of damping used. A very small amount of damping, 
B = 0.1 or less, produces practically no phase shift below resonance-, 
a sudden reversal of phase at resonance, and 180 degrees shift for 
higher frequencies. Excessive damping, B = 4 or greater, causes a 
rapid change of phase with frequency up to resonance. For values 




FIG. 4. (A) The construction of vibrator unit for the oscillograph galvanometer. 
(B) The magnet assembly for the oscillograph galvanometer. 

of u greater than one, over damping produces less phase shift than 
that resulting from insufficient damping, but for values of u less 
than one, this condition is reversed. A most interesting condition 
arises when the damping is such that B = 1.5. From Fig. 3 it is 
seen that the curve for B = 1.5 is almost exactly a straight line from 
u = to u = 1. In other words, the phase shift is directly pro- 
portional to frequency within this range. If a galvanometer which 
fulfilled the above condition were used to record a complex wave 
on a film traveling at constant speed, each of the component fre- 
quencies would be given the same linear displacement, and no phase 
distortion would result for frequencies within the range from zero 



Oct., 1930] 



GALVANOMETERS FOR RECORDING 



433 



to resonance. In the cape of a galvanometer resonating at 5000 
cycles per second with a film speed of 90 feet per minute, this dis- 
placement amounts to approximately nine- tenths of a mil. 

Nearly all of the Photophone recording units in use at the present 
time are equipped with oil damped galvanometers of the type shown 
in Fig. 4. This particular design is the one used in oscillograph? 
manufactured by the General Electric Company. The require- 
ments of an oscillograph vibrator are very similar to those for vari- 
able area sound recording. This made it possible to incorporate 
into the design of the first recorders a galvanometer which had al- 
ready been in use for many years. 




o 




FIG. 5. The construction of an improved oil damped galvanometer. 

The construction of the vibrator unit and magnet assembly are 
shown in Fig. 4. A continuous loop of thin molybdenum strip is 
stretched over an insulating bridge and around a pulley as shown. 
The two ends of this strip are fastened to the vibrator frame and 
insulated from each other. The loop is kept in tension by a spring 
which is enclosed in a housing, H. This spring acts on pulley, P, 
with a force which can be controlled by thumb nut, T. A small 
mirror is cemented to the two strips midway between the bridge 
supports. The vibrator unit is lowered into a well of oil which 
encloses the ends of two soft iron pole pieces. A small gap between 



434 



G. L. DIMMICK 



[J. S. M. P. E. 



the pole pieces accommodates the two strips. The flux from a large 
permanent magnet is concentrated in this gap in the plane of the 
strips. If a voltage is applied to the vibrator terminals, current 
passes down one strip and up the other, producing a torque, pro- 
portional to this current. The mirror, suspension, and oil form a 
damped rotational vibrating system, some of the properties of which 

A 





FIG. 6. The construction of the new dry damped galvanometer. 

have been discussed. Sufficient tension is applied to the strip to 
make the system resonate at about 5000 cycles per second. At 
ordinary room temperature, the bluntness is about seven-tenths. 
Galvanometers of this type are rugged enough to be practically 
unaffected by external vibrations and will stand considerable abuse 
without failing. When used with a reasonable amount of care, 
they are capable of making excellent sound .records , 






Oct., 1930 J 



GALVANOMETERS FOR RECORDING 



435 



Another galvanometer of the oil damped type has recently been 
designed, which incorporates several features not found in the 
oscillograph vibrator. A photograph of this galvanometer is shown 
in Fig. 8 (center), and a sketch illustrating its construction is shown 
in Fig. 5. The principal improvements are its small size, its oil- 
tight construction which enables it to be used in any position, and 
its complete freedom from external adjustments of the vibrating 
system. The mirror size, dimensions of strip, and distance between 
bridge supports are the same as in the oscillograph galvanometer. 
Molybdenum strips are used under sufficient tension to make the 
system resonate at about 6000 cycles per second. The bridge, 



IfOO 10,006 

/*& S0W& 

FIG. 7. Frequency characteristic of the new dry damped galvanometer. 



between supports, clears the suspension strips by about five 
mils. This construction provides the necessary damping with a 
thinner oil than was previously used, and results in a decreased effect 
of temperature upon damping. Two cobalt steel magnets in parallel 
furnish the necessary flux in the air gap. 

In order to keep the resonance frequency high and at the same time 
attain sufficient sensitivity, the galvanometer mirror in both of the 
previously described designs is necessarily small. Its light-gathering 
power is adequate to meet the needs of sound recording in its present 
stage. The coming of wider sound tracks and higher film speeds, 



436 



G. L. DlMMICK 



[J. S. M. P. E. 



and the desirability of using slower photographic emulsions in order 
to gain resolving power, will greatly increase the requirements as to 
light-gathering power of recording galvanometers. To meet this 
demand, a new galvanometer has recently been developed which 
utilizes a mirror of approximately fifteen times the area of the os- 
cillograph mirror. A photograph of this galvanometer is shown in 
Fig. 8 (right). Its design is a radical departure from that of the 
others described in this paper. The principal features of this new 
galvanometer are its large mirror, its method of damping without 
oil, and its rugged construction. 




FIG. 8. Comparison of three types of galvanometers. 



Work on dry damped galvanometers of the electro-magnetic 
type was started about a year and a half ago by Mr. C. R. Hanna 
of the Westinghouse Electric and Manufacturing Company. Shortly 
after this, the writer took up the idea and began work on the design 
which will be described here. Continuous development lasting for a 
period of more than a year was necessary to bring this design to its 
present form. 

In Fig. 6 is a sketch showing the general construction. A soft 
iron armature, A, is supported at the upper end of a small steel rod, 



Oct., 1930] GALVANOMETERS FOR RECORDING 437 

the lower end of which is solidly clamped to the frame. Two annealed 
silicon steel pole pieces are placed one on either side of the armature 
and fastened to the main casting. Both pole pieces are slotted at 
the ends nearest the armature to provide room for two coils of copper 
wire which surround the armature but are not in contact with 
it. The two ends of a loop of phosphor bronze ribbon are fastened 
by means of solder to the two ends of the armature, A. The loop 
of ribbon passes through slots in one of the pole pieces, and around 
a small semi-cylindrical rod, carrying the mirror. The flat side of 
this rod is provided with a groove which allows it to pivot about a 
knife edge upon which it rests. The ribbon is kept under tension by 
a spring. This arrangement is in effect a mechanical transformer 
which steps up the amplitude of the rotational vibrations of the 
armature in the ratio of about ten to one. The flux from a permanent 
magnet is concentrated in four air gaps, two at each end of the ar- 
mature. The width of each air gap is about twenty-five times the 
maximum armature displacement necessary for full modulation. 
The armature is in stable equilibrium between the pole pieces and 
has no tendency to shift from its position after it has been centered. 

Damping is effected in this galvanometer by a rubber pad placed 
between the coils and straddling the armature. This pad is of pure 
gum, long-life rubber, impregnated with tungsten powder to increase 
its mechanical resistance. 

The effect of sending a current through the two coils in the same 
direction is to increase the flux density in two diagonally opposite 
air gaps and to decrease it in the other two. A torque is thereby 
set up which is proportional to the current, up to the point where the 
armature saturates. The magnetic circuit is so designed that 
armature saturation occurs for a current about three times that re- 
quired for maximum modulation. Saturation protects the galvanom- 
eter from mechanical injury in case of abnormally large surges of 
current which often occur when the microphone receives a sudden 
jar. 

There are many advantages resulting from the use of a mechanical 
transformer for increasing the armature deflections. The smallest 
armature which it is practical to use in this type of driving unit 
weighs many times as much as the mirror which it is desired to drive. 
It can be shown that under this condition maximum mirror de- 
flection per unit armature torque is obtained when the mirror and 
armature are coupled together in such manner that the moment 



438 G. L. DIMMICK 

of inertia of the mirror multiplied by the square of the ratio of trans- 
formation is equal to the moment of inertia of the armature. The 
increased efficiency obtained in this way is utilized to increase the 
galvanometer sensitivity, to make its construction more rugged, 
and to improve its frequency characteristic. 

Fig. 7 shows a frequency characteristic taken on a galvanometer 
of this design. Constant voltage was maintained at the grid of the 
last amplifier tube while the frequency was varied. The power 
sensitivity of a dry galvanometer having the above frequency 
characteristic is greater than that of the oil damped galvanometers 
previously discussed. The relative size of the three types of galvanom- 
eters is shown in Fig. 8. 

DISCUSSION 

MR. KEU,OGG: Mr. Dimmick gave credit to Mr. Hanna for stimulating our 
work on the dry galvanometer. Mr. Hanna has told me the considerations which 
lead him to look for success in the application of this type of magnetic system 
to recording and oscillograph galvanometers. He had made an analysis of the 
iron armature type of loud speaker motor, in a 1925 I. R. K. paper. In this paper 
he established the relation between the magnetic reduction of stiffness and the 
force produced for the given amount of power from an amplifier. The analysis 
showed that the more of this magnetic reduction of stiffness you can permit, the 
more efficient you can make the motor. In a loud speaker the magentic reduction 
of stiffness is a limitation. This factor is not present in the moving coil design. 
That is why the moving coil design has won out for loud speaker drives. We didn't 
get good loud speaker reproduction until we began to use diaphragms with very 
low natural frequencies. The necessity for a very flexible mounting was such a 
handicap to the motor which depended on a magnet pulling on a piece of iron 
that that type of motor was killed. Mr. Hanna applied the same reasoning to the 
oscillograph and there the boot is on the other foot. The oscillograph galvanom- 
eter must have a high natural frequency and here a moving iron armature shows 
up to much better advantage. As Mr. Dimmick pointed out, with the same 
input from the amplifier, he is able to move a mirror of fifteen times the area 
through the same angle, and keep the natural frequency as high as with the 
standard or dynamic type, which belongs to the moving conductor class. 

MR. Ross: I should like to ask what kind of mirror is used. Unless a per- 
fectly plane reflecting surface is used, there is apt to be a good deal of light dis- 
persion causing fringing at the recording edge of the light beam introducing dis- 
tortion in recording. 

MR. DIMMICK: The mirror is made of a good quality glass and is 100 mils 
wide, 125 mils high, and 5 mils thick. We have had no trouble from the source 
which you mention. 



PROGRESS IN MICRO CINEMATOGRAPHY 

HEINZ ROSENBERGER* 

At the fall meeting in 1927 a paper on Micro Cinematography 
was given in which the usefulness of the motion picture not only 
for the demonstration of microscopic phenomena but also its appli- 
cation in medical and biological research work was described. 

The work done in the last two years has been toward improving 
the technic of taking micro cinema records and also toward the 
improvement and the standardization of the necessary equipment. 
At the spring meeting in 1929, a description of the Standard Micro 
Cinematographic Apparatus was given. With this apparatus every 
scientist is able to obtain good results as the handling of the apparatus 
is very much simplified. It is fully automatic and can be left going 
for days without attention excepting the control of focus from time 
to time and more often when higher magnifications are used. 

For accelerated film records, and most of the cell work is acceler- 
ated, the frequency, for instance 1, 2, 3, 4, 6, 8, 12, etc., exposures per 
minute can be adjusted on a dial of an electric clock. ,The length 
of exposure can be adjusted on a screw on the timing device, so also 
can the time be set when the machine should start or stop by the use 
of an additional time clock. 

The number of adjustments on the standard apparatus is now 
reduced to a minimum and therefore the handling is much simplified, 
leaving the attention of the operator mainly on the subject to be 
photographed. When an object, for instance a living cell, is to be 
photographed the following manipulations have to be done: After 
placing the slide under the microscope the object can be viewed 
through the focusing device in very much the same way as by ordi- 
nary observation. The rate of exposure is then to be adjusted by 
turning a hand on the dial to the proper number. Then a test 
strip of film can be taken and developed. Under or over exposures 
can be regulated by turning the adjusting screw of the timing de- 

* The Rockefeller Institute for Medical Research, New York. (Read before 
the Society at Washington.) 

439 



440 



HEINZ ROSENBERGER 



[J. S. M. P. E. 



vice either to the left for longer exposure or to the right for shorter 
exposure. For higher frequencies and when using arc light, the 
sector of the revolving shutter has to be adjusted. 

The main direction of our research work during the last two years, 
since the micro film was shown, was toward higher magnifications 
in order that something about the structural details of living tissue 
cells may be revealed. It was also anticipated to keep cells alive 
and under observation for a longer period of time than was possible 





With Cine Kodak Model A With Filmo Camera 

Micro cinema apparatus for 16 mm. cameras. 

before. This was accomplished by the development of a special 
culture chamber, which was manufactured with the cooperation 
of Zeiss. 

I want to point out here that the difficulties of micro cinema work 
with high magnifications increase by arithmetical progression. 
Suppose we are looking at the moon through a telescope. When 
it is a low powered telescope the moon will move slowly across 
the field of vision, due to the rotation of the earth. With medium 
powered telescopes the moon apparently will move very much 



Oct., 1930] PROGRESS IN MICRO CINEMATOGRAPHY 441 

faster across the field, while with high powered telescopes one can 
hardly follow the motion. 

The same is true with the microscope. The higher the magnifica- 
tion, apparently the faster is the speed with which the objects move. 
The faster the speed of the objects, the more frequent exposures 
we have to make. The more exposures we take per minute or second, 
the greater must be the light intensity to give the film the proper 
exposure, but the more injurious is the light to the delicate objects. 
And last but not least, the higher the power of the objective the 
less depth of focus we have in the field and the more difficult it is 
to keep the preparation in focus. I have not yet mentioned the great 
danger of transmitting vibrations from the moving parts of the 
apparatus or from some outside disturbances to the microscope, for 
naturally vibrations also are magnified. 

Magnifications are measured with an object micrometer, in which 
one mm. is divided into 100 parts. This micrometer is photo- 
graphed on the film. 

The magnifications which were mainly used several years ago 
were ranging from 60 to 120 X on the film frame. Last year's 
experiments were generally made with a magnification of about 
600 X on the film frame. In several cases, however, a magnification 
of 1250 X, which is about the limit, was used. It should be men- 
tioned here that these figures should be multiplied by about 2.5 
in order to obtain the magnifications with the same optical equip- 
ment when one looks through the microscope. The highest magni- 
fication would then be around 3000 X. Abbe claimed that the limit 
of microscopic magnification in white light is reached at about 
1500 X. 

Another point of consideration, especially when dealing with living 
cells under high magnifications, is the lack of contrast of these 
delicate structures. Very often these cells cannot be recognized 
by a layman at all when he looks through the microscope, as their 
appearance is clear as glass and there is very little difference between 
the cells and the surrounding medium. A vital stain, such as neutral 
red or Janus green, as frequently used in tissue culture work has not 
been used with high magnifications as these stains seem to have a 
deleterious effect on the cells in combination with the strong 
light. Because of some chemical reactions within the cells or else 
because of the absorption of heat, the cells either do not behave 
normally or else die very rapidly. 



442 HEINZ ROSENBERGER [j. s. M. P. E. 

It is possible, however, to increase contrasts photographically. 
It is a well-known fact that various photographic emulsions can 
reproduce an object with greater contrast than actually exists. 
It is possible to photograph, for instance, an article with very slight 
variations of gray, hardly noticeable to the human eye, so that these 
variations become almost black and white in the reproduction. 
The photographic emulsion can detect differences in shade which 
are invisible under normal circumstances. We have employed the 
above-mentioned properties with great advantage in micro cinema 
work in the detection of cell structures which are otherwise invisible. 
Motion picture records have been made, for instance, of white blood 
cells which show clearly that these cells are surrounded by an un- 
dulating membrane, much larger in area than the cell itself. Further- 
more, records have been taken of fibroblast cells in which the 
mitochondria move about like snakes. The function of these cell 
bodies is not as yet clearly understood. 

A MICRO CINEMATOGRAPHIC APPARATUS FOR 16 MM. MOTION PICTURE 

CAMERAS 

In order to enable the owner of a 16 mm. motion picture camera 
to make film records of microscopic phenomena a small and in- 
expensive outfit has been designed which has many uses in a scien- 
tific laboratory, especially where objects have to be photographed 
without going through cumbersome preparations. 

The outfit consists of the following parts: the base plate on which 
the microscope is placed, an adjustable column with two key ways 
and two set screws, a fixed plate with camera opening, a swivel plate, 
a camera holder, a combination focusing and beam centering device, 
and a telescope connecting sleeve. This apparatus adapted for the 
Bell & Howell Filmo and for the Eastman Cine Kodak Model A is 
illustrated in the figure. 

The handling of the apparatus is very simple. The microscope, 
of any make, can always be used in the ordinary way and is only 
placed on the base plate when film records have to be taken. When 
brought in line with the focusing device once it will always be in 
line thereafter, when metal strips are screwed on the base plate 
after the first adjustment. Then the connecting sleeve is put in 
place. It should hang from the fixed plate into a microscope collar 
of cardboard or metal without touching it. The object can be 
viewed through the focusing tube in very much the same way as by 






Oct., 1930] PROGRESS IN MICRO CINEMATOGRAPHY 443 

ordinary microscopic observation, using coarse or fine adjustment 
on the microscope. Then the picture can be taken at once by swing- 
ing the camera in position over the microscope. The beam of light 
needs only to be adjusted once by looking into the beam centering 
tube and at the same time turning the microscope mirror into the 
proper position so that there is an even distribution of light over the 
field. 

For general work there is practically no vibration transmitted 
from the camera to the microscope and many pictures have been taken 
even with very high magnifications, being absolutely sharp in focus. 
Sometimes, however, it may become necessary, especially when 
preparations in the "hanging drop" are to be taken, to safeguard 
them from the slightest amount of tremor. This is easily done by 
placing the microscope on a separate table and turning the entire 
upper part of the apparatus 180 degrees, so that the focusing tube 
is again in line with the microscope. The focusing and taking of 
films are otherwise done in the same manner as described above. 

Any make of 16 mm. motion picture camera can be used with this 
outfit. 

SYNOPSES OF TWO REELS 
DEMONSTRATING MOTION PICTURES OF MICROSCOPIC OBJECTS 

Reel 1. Living Cells of the Blood. 
The beating heart of a frog. 

The blood flow through arteries, veins, and capillaries. 
Various types of white blood cells. 
Macrophages from Jensen sarcoma. 
Sudden death of a macrophage. 
Cells of necturus showing thread-like pseudopods. 
Cells of necturus, high magnification, showing membrane. 
Records of cell divisions and phagocytosis. 

Reel 2. Cells of Living Tissue. 

Beating fragment of heart tissue from a chick embryo. 

Growing culture of fibroblasts, low power. 

Two single fibroblast cells, high magnification, showing details of structure. 

Normal rat fibroblast. 

Malignant rat fibroblast. 

Details of cell structures under very high magnification, nucleus, nucleolus 

mitochondria, etc. 

Rat fibroblast forming new cell branch. 
Culture of nerve fibers. 
Growing end of a single nerve fiber. 



444 HEINZ ROSENBERGER 

Pigment epithelium, high magnification. 
Cell division of afibroblast (high power). 
Cell division of a fibroblast (very high power) showing interior of cell. 

LITERATURE ON MICRO CINEMATOGRAPHY 

1 COHEN, ALFRED E-, CRAWFORD, J. HAMILTON, AND ROSENBERGER, HEINZ: 
"Cinematography of Skin Capillaries in the Living Human Subject," Proceedings 
of the Society for Experimental Biology and Medicine, XXII (1924), p. 89. 

2 ROSENBERGER, HEINZ: "Der Kapillarograph," Kinotechnik, VII (1925), 
p. 585. 

3 CRAWFORD, J. HAMILTON, AND ROSENBERGER, HEINZ: "Studies on Human 
Capillaries," The Journal of Clinical Investigation, II (1926), p. 343. 

4 ROSENBERGER, HEINZ: "Micro Motion Pictures," Sci. Amer. (March, 1927), 
p. 166. 

6 ROSENBERGER, HEINZ: "Micro Cinema in Medical Research," Trans. 
Soc. Mot. Pict. Eng., XI (1927), p. 750. 

8 ROSENBERGER, HEINZ: "Der Kapillarograph," Mikrokosmos, XXI (1927- 
28), p. 120. 

7 ROSENBERGER, HEINZ: "Mikrokinematographie im Dienste Medizinischer 
Forschung," Kinotechnik, X (1928), p. 329. 

8 ROSENBERGER, HEINZ: "Micro Cinematography," The Journal of Dental 
Research, IX (June, 1929), p. 343. 

9 ROSENBERGER, HEINZ: "A Standard Micro Cinematographic Apparatus," 
Science, LXIX (1929), p. 672. 

10 ROSENBERGER, HEINZ: "A Standard Micro Cinematographic Apparatus," 
Trans. Soc. Mot. Pict. Eng., XIII (1929), No. 38, p. 461. 

11 ROSENBERGER, HEINZ: "A Micro Cinematographic Apparatus for the 
Owner of a 16 mm. Motion Picture Camera," Science, LXXI (1930), p. 266. 

DISCUSSION 

PRESIDENT CRABTREE: Gentlemen, I think we have witnessed one of the 
finest motion photomicrographs ever made. No doubt these researches of the 
photomicroscopist are going to throw a great deal of light on metabolism and the 
causes of health and disease. 

MR. ZWORYKIN : Is this rapid motion of particles shown on the film similar to 
the Brownian movement, and is it the result of the bombardment of the larger 
particles by the random motion of the molecules with some oriented components? 

MR. ROSENBERGER: It may be that there is a flow of protoplasm inside of the 
cells. Those granules in the film are very large compared with the small ultra- 
microscopic particles, the motion of which is presumably caused by bombardment. 
I have taken a film of ultramicroscopic particles in motion (Brownian move- 
ment) of gold and silver colloids which I have here and which I can show if you 
wish. In order to shorten my paper I refrained from showing it. 



TELEVISION SYSTEMS 
C. FRANCIS JENKINS* 

So far as I am aware all the thousands of engineers who are engaged 
on television development are working on the same method of analysis 
and synthesis. 

This consists of the scanning of the object as a single point at any 
instant considered; and similarly building up the received picture 
point by point, with never a moment when there is more than a 
single point on the eye of the observer. 

There is, therefore, no picture except in the persistence of the brain 
image of these successive elementary areas. But the light points 
of the picture are assembled so quickly that the picture seems to be a 
real image, and to reside in the plane of the scanning disk, or com- 
parable mechanism. 

Persistence of vision is, therefore, an essential factor in the present 
system of television and radiomovies, just as it is in the movie 
theater. 

But this persistence of vision is thousands of times more handi- 
capped in radiomovies than it is in theater reproduction of film 
pictures. 

In theater projectors the shutter wastes half the light; but in 
television reproduction the observer sees but a twenty-five hundredth 
part of the light. 

Really, it is nearly three thousand times worse than even this first 
loss would seem to indicate; it is a loss represented by the product 
of one sum by the other. The loss is in the order of six million to 
unity. 

This, then, explains why the present accepted system of television 
cannot be expected ever to produce entirely satisfactory pictures. 
It is astonishing that we get the pictures we do ; and that is not saying 
very much, either. 

With the present method, no large pictures can be produced 

* Jenkins Laboratories, Washington, D. C. (Read before the Society at 
Washington.) 

445 



44(> 



C. FRANCIS JENKINS 



IJ. S. M. P. E. 



with the drum and quartz rod mechanism, although with this drum 
scanner we are getting the largest pictures yet obtained, but they 
are only about 6X8 inches. The drum is only an improvement 
on the disk scanner; the fundamental principle remains the same. 
In either device the light which reaches the eye is never more than 
that which gets through a single aperture, namely, that representing 
an elementary area of the picture, or about one twenty-five 
hundredth of the whole picture surface. 




Illustration of a lantern slide made up of elementary 
areas. 

I am not suggesting that the drum type scanner is to be abandoned ; 
it is the best yet found, and serves a useful purpose in the home. 
But neither the drum nor the disk can ever be made to project a 
theater picture, because no light can reasonably be expected ever to be 
found which will be six million times more intense than those now 
available, and still have the required light-change time-factor, say, a 
million light changes a second. Opportunity for development must 
be looked for in other directions. 



Oct., 1930] TELEVISION SYSTEMS 447 

A study of the problem seems logically to suggest a lantern slide 
in which the density areas of its picture are changed in accord with 
the changes in the lens image of the subject-scene at the distant 
broadcasting station. 

In standard use today we have two projection schemes to serve 
a large audience ; one is the usual magic lantern slide, a still picture ; 
the other is a moving picture, made up of a great number of stills 
projected onto the screen in rapid succession to simulate motion. 

The newly proposed scheme is a magic lantern slide, the density 
areas of which may be changed at will. That is, if these elementary 
areas of the picture could be changed in density from moment to 
moment, then the resultant picture itself would change. 

Our concept consists, as shown in the illustration, of a picture 
divided into 2304 elementary areas, i. e., 48 lines of 48 elementary 
areas in each line, much like halftone picture dots; and if these 
elementary areas or dots can be changed the picture changes, and 
we have a motion picture. 

Structurally, this new lantern slide consists of a cellular structure 
of 48 rows with 48 cells in each row. These cells may be of any 
desired size, for example, a quarter inch square, making up a lantern 
slide one foot square. 

It resembles a honeycomb, with miniature square cells 4 inches 
long. These are built up of 48 glass strips, 12 inches long and 4 inches 
wide. The strips are set into a frame fixedly at top and bottom. 
Between these vertical glass strips, other little strips of glass, about 
Y 4 inch wide and 4 inches long are placed like shelves, the whole 
making a cellular frame having a combined one foot square clear 
opening therethrough. 

Now if a satisfactory scheme could be devised for closing at will 
each of these tiny cells, dark areas could be built up, and these dark 
areas might easily represent figures. And changing the figure means 
only that some of the closed cells would be opened and new ones 
closed. If this rearrangement is completed every fifteenth of a 
second, for example, a motion picture results. And again as these 
changes are made by incoming controlled radio signals, each change 
of figure represents the image at the distant broadcast station. 

Now for opening and closing the cells, there is in each cell an 
electrostatic valve of aluminum foil. Bach foil blade lies on the 
floor of the cell, and is changed by voltage-amplification of the in- 
coming radio signals. Each charge either closes the cell for totality, 



448 C. FRANCIS JENKINS [J. s. M. p. E. 

or only partially closes it for halftone values. The values must 
also discharge in one tenth of a second at longest to make good 
motion pictures; and are in staggered relation to prevent mutually 
induced capacities. 

Now to project this changing figure onto a theater screen, it is only 
necessary to place an arc light, or other acceptable light source, 
behind this cellular lantern slide; and to put a projection objective 
in front of it to image this changing lantern slide figure on the screen 
in front of the audience. 

Perfectly simple, isn't it? I hope some day to say it is simply 
perfect, and to demonstrate it by actual transmission of radiomovies 
from our broadcast station, and projected reception of the same at 
one of our subsequent Society conventions. 

So the day seems now within sight when distant scenes and events 
may be reproduced on the screens of theaters; and when motion 
pictures will be distributed from Hollywood to the nation's theaters 
direct by radio instead of film. 

DISCUSSION 

MR. K. D. COOK: As I understand it, there were 48 lines with 48 elements 
in each probably about 2500 dots which had to be reproduced about 16 times 
per second and this makes about 40,000 cycles for pictures now being sent by 
Mr. Jenkins' station. I was interested in the way the cells were actuated to 
reduce the speed requirements of each cell and in the problem of bringing the 
frequency mentioned before into the broadcasting station from an outside source. 
I should think that every time the weather changed the signal would vary so 
much that it would give trouble in the picture. 

MR. JENKINS : The contact for each cell has identically the same time factor 
as is employed in the single light spot. That factor has not been changed, but 
the light valves have 1/15 second action time instead of 1/35,000 second. That 
is probably the greatest merit of the system. We are setting up a multiple plate 
for a fixed source of light to be projected on the screen. I have spoken of it as a 
lantern slide because it is fixed. If we make the elementary picture areas, factors 
to control at will, we have a changing picture on the screen. The time factor is 
identical in both schemes and is the contact time. This is the same as the dura- 
tion time of the signal representing that area 1/2304 second. 

MR. COOK: How about the transmission line? Do you have trouble there? 

MR. JENKINS : I don't think so, because we have been broadcasting for almost 
two years, and our reports have come not only from amateurs but also from the 
radio supervisors of three radio districts. The supervisor for the district includ- 
ing Detroit is one of the most enthusiastic boosters for the scheme we employ. 

MR. Ross: I should like to ask if a differing transmission frequency is used 
for each valve. 

MR. JENKINS: No, the radio signals are distributed by commutator to each 
cell in turn. 



Oct., 1930] TELEVISION SYSTEMS 449 

MR. GAGE : To those familiar with the work which has been done on television 
in the past, particularly with the device using such a distributor as set up in the 
Bell Telephone Laboratories, the practicability of the whole thing is apparent 
provided we can get a cell which will respond as Mr. Jenkins suggests, and it is 
only necessary to construct one cell which can be reproduced, and then we can 
make as many million as we desire. I should like to ask if any of these cells have 
been constructed that are satisfactory. 

MR. JENKINS: Yes, we built 36 elementary cells 6 each way. Each little 
valve is an independent thing, to be pulled out with your fingers for repairs. 
You make any modification you like and put it back. I should like to take oc- 
casion at this point to call your attention to what the Bell Telephone Company 
did in the twisted neon tube cell. No one of these elementary areas persisted in 
luminosity, and that is particularly the merit of the new scheme. As long as our 
eye is employed to maintain the persistence of the apparent glow of each spot, 
we have gained nothing, but if we can substitute persistence of valve action to 
produce persistence of light of each elementary area we have solved the problem. 
That is the distinction between the long neon tube with tinsel spots fastened to 
the back of the glass, employed by the Bell Company. I don't think my idea 
was ever anticipated. Remember we will never succeed in radiomovie projection 
as long as we depend on persistence of vision to complete the image. It must be 
completed in the mechanism itself, and not built up in our heads. There is no 
picture on the whirling disk or drum, as there seems to be. When you slow the 
motor to a stop you find you have been looking at one spot only and the picture 
was built up in your brain. But the new picture can be photographed with the 
snapshot camera. If the Doctor will make a liquid cell for us and sweep across it 
radiation of some kind causing varying densities where the radiation strikes the 
cell, I will give him a million dollars for it, because I can then sell it for ten. 

MR. TAYLOR: If Mr. Jenkins would be satisfied to show slow action, it would 
not be necessary to use so many light charges. Usually in television we have a 
close-up of a person talking. Such a picture might be shown with materially 
less than 16 a second and the screen image would be just as bright. 

MR. JENKINS: That is true, but it seems hardly worth while to tackle any- 
thing but the hardest problem first. If we expect to distribute motion picture 
plays from Hollywood by radio, we might as well accept the difficult situation 
as it stands. So we have built a valve having 1/10 second action time. Thus 
we have solved the problem, and if we can get one satisfactory valve acting that 
fast, we have only to multiply it by the number needed for the entire lantern 
slide. 

We have found a pair of satisfactory blades, the heavy one of which is 0.008 
inch thick, the other of aluminum foil ; we slide it into the cell so that it will be 
held on the floor of each of the little cells, and as we slip it in, it makes contact 
with the wire. These are parallel to the projection light so as not to interfere 
therewith. The wires with their insulation are only equal to that of the glass thick- 
ness, that is, lantern slide glass cut into strips. On top of the fixed blade is the 
one of movable foil. We are using 15 pictures a second because we want to use it 
to receive pictures from our broadcasting station at that rate. If we want to use 
synchronous motors we tackle only one problem at a time as both motors would 
be in synchronism with the power house. We do know that 15 pictures a second 



450 C. FRANCIS JENKINS 

are quite possible with these electrostatic valves. I have not mentioned why the 
valve blade performs so fast. In front of the charging blade of the signal dis- 
tributor is a discharging blade so that if the valve is not to be recharged on the 
second trip of the distributor, the valve is discharged and shuts down, and light 
passes through ; but if it is again charged on the second trip around, the discharg- 
ing valve drains the static charge off the valve so that it doesn't stay open. Ob- 
viously we can have light passing through the cells all the time and then make the 
valves close to build up the shadows, or have them closed all the time and open 
them for our pictures. 






MODERN PRACTICE IN INCANDESCENT CINEMA STUDIO 

LIGHTING* 

W. A. VILLIERS 

The following notes are intended to give a brief description of 
methods of incandescent lighting employed in British studios with 
particulars of the theory and design of some of the apparatus used, 
showing how this apparatus differs from Continental and American 
practice. 

There are a great many difficult problems involved which have 
needed the combined experimental and research work of studio 
engineers and equipment manufacturers. 

A great deal of such work has been done here during the last few 
years so that some of the British studios now have incandescent 
equipment which is superior to any such equipment in other countries. 

A good many different types of lighting units are used in the 
production of a picture, but for descriptive purposes these may be 
conveniently grouped under five headings: 

1. General lighting over the whole set. 

2. Lighting for close-ups. 

3. Spotlighting. 

4. Sunlighting. 

5. Effect lighting. 

All of these are probably not used on any particular set, but the 
lamps and fittings required for each type of lighting are distinct and 
made for their own particular function to give a certain intensity 
of illumination over a certain area. 

For general lighting a flood of lighting is required over the set. 
The intensity of illumination depends largely on the character of 
the set and the methods of the cameraman ; some cameramen 
use a great deal of light and stop down; others prefer to use larger 
apertures and less light. An average illumination for general lighting, 
however, is about 400 foot candles. 

* Read before the London Section. 

451 



452 W. A. VILLIERS [J. S. M. P. E, 

The lighting units employed for general lighting consist of banks 
of lamps having a reflecting surface behind them which are slung over 
the set. Various sizes of lamps have been tried but 1500 watts is 
now becoming standard. 

These overhead units are designed to accommodate different 
numbers of lamps, the most used sizes having 4, 6, and 12 lamps 
(See Fig. 1.) Tests have been carried out on many materials foi 
these reflectors. First of all mirrored glass was used and was found 
to be very efficient, the reflection factor being about 85 per cent 
It had disadvantages, however, in that it was fragile, expensive, and 




FIG. 1. Overhead lighting unit. 

extremely heavy, also difficulties were experienced due to the silvering 
failing under the action of heat from the lamps. It is still employed 
in some general lighting fittings in America. 

Chromium plated brass and stainless steel have also been tested. 
These again, while being fairly efficient 57 per cent for stainless 
steel and 63 per cent for chromium plate are heavy, expensive, 
and deteriorate under the action of heat. 

The next material used was white enamelled sheet steel. This 
is comparatively light, has a reflection factor of 75 per cent when 



Oct., 1930] MODERN PRACTICE IN STUDIO LIGHTING 453 

new, and is inexpensive. Reflectors made of this material have 
been successfully used in a number of studios, and are still employed 
in some. In Germany practically all bank type fittings are con- 
structed of this material. 

The latest practice in this country is to use polished aluminum 
as this has the advantages of white enamelled sheet steel, together 
with the most important advantage of extreme lightness. Its 
reflection factor is approximately 76 per cent and this does not 
deteriorate greatly during use. 

For general lighting and close-up lighting from the floor similar 
bank type units with a number of lamps mounted on stands were 
at first used, and this is still done to a large extent in German studios. 
It has been found more convenient here, however, to make use of 
single lamp units and flooded spotlights for general side lighting 
as these are more mobile and the lighting may be made more flexible. 

The close-up fitting most generally used here consists of a simple 
rectangular aluminum reflector fitted with one 1500 watt lamp and 
mounted on a telescopic stand, provision being made for diffusers 
in front of the lamp. 

For these close-up fittings mirrored glass has also been tried and, 
in fact, a circular mirrored glass reflector is largely used in America 
at the present day. We found, however, that the silvering de- 
teriorated under the action of heat and that aluminum reflectors 
gave better results with less cost. 

For spotlighting very high intensities indeed are required in order 
to produce high lights in a scene which is already brilliantly illumi- 
nated to, say, 400 foot candles. The actual intensity required varies 
from about 500 to 4000 foot candles. 

In Germany and in America the first incandescent cinema studio 
spotlights used were adapted arc lamps with the carbons removed 
and an incandescent lamp substituted. Later models have had a 
number of alterations made but in general they follow arc lamp 
practice very closely. 

In this country spotlight apparatus has not been evolved in this 
manner but designed from first principles and the lamps and lamp 
houses have been designed together in order to obtain the maximum 
efficiency and greatest ease in operation. (See Fig. 2.) 

Various optical systems were tried out with numbers of different 
kinds of lamps, mirrors, and lenses. A lot of tests were carried 
out with rough models at Elstree before the spotlights were actually 



454 W. A. VILLIERS [J. S. M. P. E. 

manufactured and many designs were tried out and discarded before 
a satisfactory spotlight was made. 

The requirements of the studios are that the spotlight should 
give a very high intensity with even light over the area of the spot, 
that is to say, there should be no black center or filament image; 
the light must be variable from almost parallel to a wide angle beam. 

It was found that the best all-round results were obtained with a 




FIG. 2. Spotlighting unit. 

ground glass parabolic mirror of special focus used in conjunction 
with a 3 kw. projector lamp. The filament of the lamp is curved 
roughly to the contour of the mirror so that the whole of the filament 
may be brought near the focus of the mirror. 

At first, difficulties were experienced due to overheating and 
melting of the glass bulbs when the lamps were burned at large 
angles. This difficulty was overcome by using a harder glass and 



Oct., 1930] MODERN PRACTICE IN STUDIO LIGHTING 455 

altering the position of the filament in the bulb. The spotlight 
mirrors are made detachable, and three types of mirrors may be used: 

1. Parsons parabolic, which is the most useful. 

2. Facetted glass for greater diffusion. 

3. Polished aluminum which gives a softer beam than 
the silvered glass. 

In front of the lamp provision is made for two diffusing glasses. 

Another type of spotlight that has been developed is known as an 
effect spotlight. The object with this spot was to obtain the highest 
possible intensity from the smallest practicable spotlight. A special 

2 kw. lamp is used which has a 6 in. diameter bulb. 

As the spotlight must be very small, it is not feasible to employ 
the same optical system as that with the 3 kw. lamp house because, 
if a parabolic mirror were used, most of the light issuing from the 
spotlight would have first to pass three times through the bulb of 
the lamp, resulting in inefficiency. The German practice is to com- 
promise by making the spotlight considerably larger and using a 
facetted parabolic mirror. 

In this country we collect the light with a spherical mirror which 
reflects it back on to the filament. In front of the lamp is placed a 
special lens which is made of short focus so as to reduce the over-all 
length of the spotlight and to enable the lamp to be brought near 
to the lens for high efficiency. This lens is not thick like a normal 
short focus lens but is of stepped construction in order to keep its 
absorption low. 

The American practice for small effect spotlights is to use a similar 
optical system but with an ordinary thick longer focus lens in front 
as is used on condenser arcs. For this reason the American effect 
spotlights are larger and less efficient. 

For sunlighting much higher intensities are required even than for 
spotlighting, a normal figure being of the order of 4000 foot candles 
so that the maximum candle power in the beam of the lamp must 
be three or four million; 5 and 10 kw. incandescent lamps are used 
in a lamp house having very much the same optical system as the 

3 kw. lamp house. With these 5 and 10 kw. lamps special construc- 
tion is necessary in order to get the heavy current of 50 and 100 
amperes into the glass bulb without cracking the glass. Further 
problems are also introduced due to the power of the lamps and the 
heat which they produce. 



456 W. A. VILLIERS [J. S. M. P. E. 

The effect of excessive heat on a lamp is to increase the tendency 
toward blackening of the bulb due to particles of metal thrown off 
from the filament, and several methods have been employed to over- 
come this difficulty. Lamps have been manufactured in this country 
with cooling chimneys above the filament so that the hot gas inside 
the lamp rises up the chimney and any blackening that occurs, does 
so at the top of the chimney. This method succeeds in its object 
but is very expensive and it is difficult to accommodate a lamp having 
a long chimney over the filament in a lamp house which must be 
tilted at various angles. 

In other lamps blackening is allowed to form and tungsten powder 
is introduced into the bulb so that, when the lamp is inverted, the 
blackening may be partially cleaned off by rinsing the powder round 
the bulb. This method has found particular favor in America. 

The method which is employed in the latest British projectors 
which are probably the largest successful ones that have been con- 
structed for incandescent lamps is to make the bulb comparatively 
large and to cool it by means of a silent air blower. It is also kept 
vertical by gearing for all positions of the lamp house. 

With very large incandescent lamps it is desirable, for reliable 
service, to start the lamps up gradually through a resistance because 
the filament itself has a very small resistance when cool and, if it were 
switched directly on to the mains, approximately 14 times full load 
current, that is to say, over 1000 amperes would flow. The resis- 
tance is made in a separate unit and is arranged with an automatic 
self-resetting circuit breaker in such a manner that it is impossible 
to switch the lamp on without going through the resistance, and it 
is necessary to pause for about a second at each step of the resistance. 

The 3 kw. spotlight produces 1500 foot candles at 10 ft. distance, 
800 at 15 ft. distance, and just over 500 at 20 ft. The 2 kw. spotlight 
also gives about 1500 foot candles at a distance of 10 ft. and about 
750 foot candles at 15 ft. With the 10 kw. projector an intensity 
of about 6000 foot candles is produced at 10 ft. and 2500 at 25 ft. 

Heat from Incandescent Lamps. When incandescent lamps were 
first used it was found that the heat produced was somewhat op- 
pressive, this being due to the fact that with incandescent lamps most 
of the heat is radiant, whereas with arc lamps it is conducted and 
convected. Thus, people working in the set feel the effects more 
with incandescent lamps. 

In order to obtain some idea of the heating effect of various spot- 



Oct., 1930] 



MODERN PRACTICE IN V STUDIO LIGHTING 



457 



lights at different distances some tests were made a few days ago. 

If a thermometer is placed in the beam of a spotlight and a reading 
taken, this reading has practically no value as it depends chiefly 
on the reflection and absorption of the thermometer. For our tests, 
therefore, we first measured the reflection factor of a lot of human 
faces, finding the average to be about 50 per cent. 

We then constructed a disk of chromium plated brass equipped 
with a thermopile and painted it to a reflection factor of 50 per cent. 
We used chromium plated brass so that there should be no appreci- 
able absorption from the reverse side. Tests were then made holding 
the disk in the middle of the beam from a spotlight at various dis- 
tances, readings being taken of temperature rise after steady condi- 
tions had been reached. It was found that conditions became 
steady after about 10 minutes. 



Temperature rise of test 
surface in C. 

CN O 01 
























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-- .. 


_ 









15 2U 3U 40 

Distance from projector in feet. 

FIG. 3. Variation of temperature with distance from 3 kv. 
spotlight. 

Fig. 3 shows the results of these tests for the 3 kw. spotlight. 
It is interesting to note how rapidly the temperature rise falls off 
as the distance from the spotlight increases. 

The problem of heat is now becoming very much less acute for a 
number of reasons: 

1. There is a tendency to use much larger lens apertures which 
means less light is required and less heat produced. Recently, 
a British firm of lens makers has produced a new //0.95 lens. 

2. There is a tendency in this country to use more spotlights in- 
stead of bank type illuminators. The spotlight produces more 
light in proportion to heat than the bank type fitting. 

3. There is now a more proper understanding of studio ventila- 
tion requirements and, in the latest studios, there is a complete 
change of air at least twice in every hour. 



W. A. VILLIE&.S [J. g. M. P. . 

4. Faster film emulsions are being made which again reduce the 
amount of light required and, therefore, heat. 

5. Research work is still being actively carried out in the endeavor 
to increase the intensities of incandescent spotlights, and it 
is probable that these intensities will be materially improved in 
the near future. 

6. Glass screens have been devised and are now being tested out 
for absorbing radiant heat from the lamps. 

Color. Even for black and white film the color of the light 
is very important, and it was the coming of panchromatic film 
which has led to the use of incandescent lamps. 

It seems likely that in the near future we shall have an era of 
colored films just as we have had an era of talking films during the 
last year, and with colored films the spectral properties of the light 
are even more important. 

It is possible to use color carbons but the light from these tends 
to cover limited spectrum bands. With incandescent lighting the 
whole of the visible spectrum is covered and the amount of light in 
the various parts of the spectrum may be readily altered by varying 
the filament temperature of the lamps. 

DISCUSSION 

MR. CLARK: There are one or two points which struck me. One of these 
concerns the method of measuring temperature. Mr. Villiers has devised a 
means of getting some idea of the temperature at various distances from the spot- 
light by taking a plate which has an absorption characteristic similar to that of 
the human face. I wonder if he has taken into account the fact that the plate 
probably bore no comparison to the face from the point of view of heat capacity 
and conductivity of the human flesh. I think the figures given may not really 
give any real impression at all. I would like to be corrected if I am wrong. 

You raised the question of heat absorbing glass. I do not know of any English 
manufactured heat absorbing glass which does not break when it gets hot. There 
are, however, glasses of Continental make which have a transmission for visual 
light as high as 70 per cent. 

MR. VILLIERS: Dealing with Dr. Clark's point that the temperature measure- 
ments we made are of no practical value, I submit that these temperature measure- 
ments were made to determine the effect on people in the set. Now if you are 
under a fairly hot light your skin feels the heat ; it is not inside your head you feel 
it but on the surface, and it was an endeavor to get the measurement of tempera- 
ture of a surface which absorbed, in effect, approximately the same amount of 
heat as the human being would. They did not attempt to be accurate experi- 
ments, but they are, I think, an approximation. What they do show is the way the 
heat falls off with distance under these conditions and I think it is quite fair to 



Oct., 1930] MODERN PRACTICE IN STUDIO LIGHTING 459 

assume that the effect of heat on someone's face would fall off in about the same 
manner. 

With regard to Dr. Clark's second point I was very interested to hear about the 
absorbing glass he has been testing out. As a matter of fact I think I heard about 
t it the other day from our own research laboratories and I can tell Dr. Clark that 
we are investigating types of glass of this kind at the present moment, although 
I personally do not think it is the most important method of getting rid of the 
heat. I think the most important method is increasing the efficiency of the 
spotlight which is being rapidly done. 



ONE TYPE OF ACOUSTIC DISTORTION IN SOUND PICTURE 

SETS 

R. L. HANSON* 

The addition of sound to motion pictures has introduced many 
new problems in acoustics which have heretofore been subjected 
to but meager quantitative analysis. Judgment of "good" or 
"bad" acoustics has been based on the results of direct listening 
rather than on those of sound recording. A room or sound picture 
set may be acoustically good for binaural listening at a given place 
but may not be good for recording with a microphone placed at that 
particular position. One reason is that when one listens to a sound 
he uses two pick-up devices, the two ears. Any distortion of the 
sound at one ear may be balanced by that which the second receives. 
In the case of recording we use a single pick-up device, a microphone, 
which sends on to the sound record any distortion which may be 
present at the point where it is placed. Due to the fact that the ears 
add sound effects without reference to phase while multiple micro- 
phones combine amplitudes, the use of two microphones does not 
accomplish the balancing process obtained by the ears. Distortions 
of the sound field at the position of the microphone should, therefore, 
be avoided. If a sound record is to give a satisfactory reproduction 
of the original sound, the microphone must be placed at a point 
where the intensities of all the frequencies bear the same relation 
to each other that they did near the source.** Any departure from 
this relation results in distortion. One of the main causes of this 
type of distortion is the interference at the microphone of two or 
more sound waves coming from the same source by different paths. 
While this phenomenon is not novel, the character and extent of the 

* Bell Telephone Laboratories, New York. (Read before the Society at 
Washington.) 

** Either dead or live room conditions will satisfy this requirement provided 
that in the latter case the reverberations are well diffused. Of course a distorted 
sound field may in some instances be desirable in order to reproduce the condition 
being portrayed. 
460 



ONE TYPE OF ACOUSTIC DISTORTION 



461 



distortion which it introduces in sound picture recording has not 
been fully appreciated. Recent experiments carried on in the 
Bell Telephone Laboratories have shown that this distortion is 
responsible for a hollow unnatural quality when it occurs in sound 
picture records. 

The experimental work consisted of making a study at various 




1000 2000 3000 

FREQUENCY IN CYCLES PER SECOND 



FIG. 1. Variation of intensity level at microphone located as shown in Fig. 2. 




FLOOR 

FIG. 2. Paths by which sound from source, S, may reach microphone, M, 
when located in the neighborhood of two reflecting surfaces. 

points in a sound stage of the relative intensity level resulting from 
the sound given out by a loud speaker connected to a constant fre- 
quency oscillator. The number and nature of the reflections were 
controlled by means of hard flats and absorbing material properly 
placed relative to the source. The distortion of the sound at any 
given point was determined by comparing the relative intensity level 



462 



R. L. HANSON 



[J . S. M. P. tj. 



at the point with that near the source for frequencies from 50 to 6000 
cycles per second. 

Fig. 1 shows a curve taken with a 12 X 12 foot reflector placed 
about 4 feet from the loud speaker. The microphone, which was 
12 feet away, received sound which traveled from the speaker by 
four different paths illustrated in Fig. 2. The vertical axis in Fig. 1 
shows the relative intensity level, while frequencies are shown on 
the horizontal axis. It should be noted that variations in level of 




1000 2000 3000 

FREQUENCY IN CYCLES PER SECOND 



FIG. 3. 



Variation of intensity level of sound at a microphone 10 feet from 
a source 5 feet above a reflecting floor. 



RELATIVE INTENSITY IN db 
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FIG. 4. Relative intensity level of sound at a point near the source. 



30 db. were obtained between certain frequencies. A simpler case 
involving a single reflection from the floor is shown in Fig. 3. The 
distortion is evidenced by comparison with Fig. 4 which represents 
the relative intensity level given out by the source over the same 
frequency range. This curve was made with the microphone about 
six inches from the source and shielded from all reflections. The 
difference between the two curves represents a gain frequency 
characteristic between the sound source and the microphone. Such a 






Oct., 1930] 



ONE TYPE OF ACOUSTIC DISTORTION 



463 



characteristic plotted on a logarithmic scale is shown in Fig. 5 for the 
case of a loud speaker and microphone separated by 10 feet, each 
being 5 feet above the bare floor. The difference between the length 
of the path of the sound traveling directly from the loud speaker to 
the microphone and that of the sound reaching the microphone after 
reflection from the floor was in this case 4.14 feet. Fig. 6 (A) shows a 
similar characteristic taken under the same conditions except that 
the distances were changed as shown, the path difference, however, 
remaining 4.14 feet. As much distortion would be introduced, into 
a sound record made under these conditions as would be introduced 
by any other unit of the recording system having a similar gain 
frequency characteristic. Curve B, Fig. 6, represents the result 




FREQUENCY IN CYCLES PER SECOND 

FIG. 5. Gain frequency characteristic between source, S, and microphone, 
M, located as shown. 

obtained by reducing the intensity of the reflected wave with sound 
absorbing material. The similarity to curve A at the low frequency 
end is due to the lower absorption of the material for that region. 
After removing all reflecting surfaces, and substituting a second 
microphone 14.14 feet from the loud speaker and combining the 
outputs, the curve shown in Fig. 7 was obtained. The distance 
14.14 feet from the loud speaker to the second microphone was chosen 
in order that the distances traveled by the two sound waves before 
reaching the microphones differed by the same amount as did those 
of the direct and reflected waves in the other cases, namely, 4.14 
feet. The resulting phase relations were, therefore, the same in 



464 



R. L. HANSON 



[J. S. M. P. E. 



all cases. It is evident from these results that the distortion which 
has been commonly noticed with multiple microphones is basically 
of the same type as that introduced by reflecting surfaces. 

The explanation of these phenomena is simple. Let us consider 
the case of the microphone 10 feet from the loud speaker, both being 
5 feet above the bare floor. The sound which reaches the micro- 
phone travels by two paths, one directly from the loud speaker and 
the other from the loud speaker to the floor and then by reflection 
into the microphone. Since the reflected wave travels a greater 
distance than the direct, there will be certain frequencies for which 




3456789 2 

100 1000 5000 

FREQUENCY IN CYCLES PER SECOND 

FIG. 6. 04) Gain frequency characteristic between a source and micro- 
phone located as shown. (B) Characteristic obtained after reducing inten- 
sity of reflected wave by the introduction of absorbing material on the floor. 

the two waves arrive at the microphone 180 degrees out of phase. 
There will be other frequencies for which the two waves arrive in 
phase. The intensity level at the microphone will be greater or 
smaller than that which would have resulted from the direct wave 
alone, depending upon whether the phases are such that the ampli- 
tudes of the waves add or subtract.* In the case of the two micro- 
phones we have a similar phenomenon except that the interference 
takes place between the output currents. If for any given case we 

* It is assumed, of course, that the reflector is large enough to give complete 
reflection at all frequencies of interest. 



Oct., 1930] 



ONE TYPE OF ACOUSTIC DISTORTION 



465 



know the difference in the lengths of the paths traveled by the two 
waves, we can calculate the frequencies for which they will be in 
phase or 180 degrees out of phase. The intensity of the wave which 
has traveled the longer path will be lower than that of the other 
and hence, even though they may be out of phase, there will not 
be complete neutralization. If we know this difference in path 
length and the fractional part of the energy absorbed by the re- 
flector we can calculate for a few simple cases the resulting intensity 
level for any frequency. Such a calculated curve for the case of a 
microphone and speaker 5 feet above the concrete floor and separated 
by a distance of 10 feet is shown in Fig. 8. The peaks come at those 
frequencies for which the two waves are in phase while the dips come 
at those frequencies for which the two waves are 180 degrees out of 




-12 



100 



456789 2 3 

1000 
FREQUENCY IN CYCLES PER SECOND 



56789 

10,000 



FIG. 7. Gain frequency characteristic between source and the combined 
outputs of two microphones located as shown. 

phase. The frequencies at which the peaks and dips occur, and also 
the total variation of intensity level of 15 db. correspond very 
closely with the results shown by the experimental curves. The 
zero line represents the level which would have been obtained by 
the direct wave only. The distortion of the sound field at the 
microphone is dependent upon the difference in level resulting when 
the two interfering waves are in phase and that when they are 180 
degrees out of phase. This is represented on the curve by the 
difference in level between the peaks and the dips. Fig. 9 (A) shows 
the manner in which the maximum difference in intensity level 
depends upon the ratio of the distances traveled by the two inter- 
fering waves, neglecting absorption by the reflector. For example. 



466 



R. L. HANSON 



[J. S. M. P. E. 



this curve shows that in order that the maximum variation in level 
at a point shall not be over 2 db., a reflected sound must have traveled 
eight and one-half times as far as the direct sound. If part of the 
energy of the wave is absorbed during reflection, the maximum varia- 
tion in level is reduced. Curve B of Fig. 9 represents the conditions 
if the reflected wave has had 20 per cent of its energy absorbed at 
the reflecting surface. Thus it is clear that the undesirable effect 
of reflecting surfaces can be reduced by increasing their distances 
from the sound source and microphone. 

These results show that even if we have but a single reflecting 
surface too near a speaker or microphone the sound reaching the 




-12 

2 3456789 2 34 

100 1000 5000 

FREQUENCY IN CYCLES PER SECOND 

FIG. 8. Theoretical gain-frequency characteristic between a sound source 
and microphone separated by 10 feet, each 5 feet from a reflecting surface 
which has a reflection coefficient of 0.95. 

microphone may be badly distorted from its original quality as cer- 
tain pitched sounds are accentuated while others are greatly reduced 
in intensity. Since the quality of a voice is dependent upon the 
frequencies present and their relative intensities, any system which 
changes these relative intensities will change the quality. If the 
speaker alters his position relative to the microphone and reflector, 
he at the same time changes the phase relations of the direct and 
reflected sound waves as they strike the microphone and therefore 
not only the original voice quality is distorted but the resulting 
quality will vary as he moves from place to place. 

Experimental sound records made under conditions where dis- 



Oct., 1930] 



ONE TYPE OF ACOUSTIC DISTORTION 



467 



tortion due to interference existed, as illustrated in Figs. 5, 6, and 7, 
show an unnatural quality which is designated by some listeners 
as " hollow." One example is a record made of a speaker sitting at a 
table. The microphone was suspended about three feet from the 
speaker as shown in Fig. 10 (^4 ) . The quality of the reproduced sound 
from the record was very unnatural and hollow. A second recording 
was made placing the microphone just below the table top, as shown 
in Fig. 10 (B), care being taken to so place it relative to the table top 
that the direct wave was not interrupted. The resulting quality 



lATION OF INTENSITY LEVEL IN db 
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RATIO OF DISTANCES TRAVELED BY TWO INTERFERING WAVES 

FIG. 9. (A ) Showing the way in which distortion due to the interference 
of two sound waves may be decreased as the ratio of the distances traveled 
by the two waves is changed. (B) Showing the effect of absorbing 20 per 
cent of the energy of one of the interfering waves. 



obtained on the reproduced record was natural and entirely lacking 
in the hollow quality previously noted. The difference in the two 
cases lay in the fact that in the first the microphone received not only 
the direct wave from the speaker but in addition one reflected from 
the table top. In the second case the only sound reaching the 
microphone was that coming direct from the speaker. 

To verify the conclusion that this hollow quality is the result of 
distortion caused by acoustic interference the following experiment 
was made. Two disk speech records pressed from the same matrix 



468 



R. L. HANSON 



[J. S. M. P. E. 



were placed on two accurately synchronized turntables. Two 
similar phonograph reproducers connected in series were placed on 
the two records and their positions so adjusted that the currents 
generated by them had the same phase relation as did the interfering 



-il- ~ "t 



TABLE 



FIG. 10. (A ) An arrangement of speaker, S, and micro- 
phone, M , which would result in a sound record of poor 
quality due to the interference at M of the direct sound 
and that reflected from the table. (B) The location of 
the microphone in a position such that it receives the 
direct sound only. 

sound waves at the microphone in the acoustic case. For example, 
to simulate the phase relation of two sound waves having a path 
difference of 4.14 feet, as in the case illustrated in Figs. 5 and.6, the 
needles on a seven inch radius of a 33 l /s rpm. record must^be sepa- 



Oct., 1930] ONE TYPE OF ACOUSTIC DISTORTION 469 

rated by 0.096 inch. With the effective separation of the needles on 
the two records thus adjusted, the quality of the reproduced sound 
was similar to that obtained from sound records made under condi- 
tions where acoustic interference took place at the microphone. 
The natural quality of the record was restored by bringing the needles 
to corresponding points on the two records so that the generated 
currents were in phase and no interference existed. The quality 
in this case was the same as that obtained by using one reproducer. 
Thus it was shown that interference between the currents generated 
by two phonograph reproducers when properly separated gave rise 
to the hollow quality in question. 

Due to restrictions placed by the camera on the choice of micro- 
phone positions, the solution of the problem of interference in sound 
picture sets is not always a simple one under practical studio con- 
ditions. The most obvious solution is to eliminate reflecting surfaces 
in the immediate neighborhood of the sound source and microphone. 
In cases where this is not possible, conditions can be improved by 
either of two methods: by so placing the microphone relative to 
the source and reflector that it does not receive the reflected sound 
as was done in the case previously described, or by covering the 
reflecting surfaces by highly absorbing material thereby reducing 
the intensity of the reflected wave. 

It is not the intention of this paper to imply that dead recording 
is preferable to live recording. The effect here described is caused 
by discrete reflections and is entirely different from that caused by 
the diffused reflections in a reverberant room. 

SUMMARY 

These experiments have shown that reflecting surfaces in a sound 
picture set may give to that part of the recording system between 
the sound source and the microphone a transmission characteristic 
which would not be tolerated by any other component part of the 
system. The distortion caused by acoustic interference was shown 
to be very similar to that obtained electrically by two microphones. 
Experiments performed with two phonograph reproducers on syn- 
chronized disk records verified the conclusion that interference can 
give rise to the distorted quality, observed in sound records made 
under conditions where interference existed. This acoustic distor- 
tion can be eliminated in sound picture sets by elimination of re- 
flecting surfaces in the immediate proximity of the speaker, the 



470 R. L. HANSON [J. s. M. P. E. 

proper placement of the microphone, or by reducing the intensity 
of reflected waves by means of absorbing material placed over the 
reflecting surfaces. 

Note. The presentation of this paper before the S. M. P. E. was accompanied 
by a sound picture demonstrating the effect on speech of interference caused by 
reflecting surfaces or multiple microphones. 

DISCUSSION 

MR. COFFMAN: There is a marked analogy observable between the effects 
produced in recording by differences in microphone placement and those effects 
produced in photography by differences in focal length. In the demonstration 
material just exhibited, the microphones and the reflecting surfaces were both 
close to the speaker, and the acoustic perspective was quite different from the 
photographic perspective. The low ratios of the distances, speaker to micro- 
phone, speaker to reflecting surface, and reflecting surface to microphone, tend to 
produce recording results comparable to the characteristic photographic distor- 
tion caused by the use of lenses of too short focal length. As is well known, the 
use of short focal length lenses to photograph a subject with feet extended toward 
the camera results in a picture in which the feet are of huge size. Similarly, the 
low distance ratios in this case result in an abnormal proportion of the reflected 
sound, which also has a large phase difference with the direct sound. Neither of 
these conditions would be present if the microphone were comparatively distant 
from the speaker as related to the speaker's distance from the reflecting surface. 
Do experiments with a set-up of this kind indicate the same type of distortion as 
was evidenced in the demonstration? 

MR. HANSON : Over fifty records, similar to those shown, taken under condi- 
tions where the distances between the source, microphone, and reflector were 
varied over a wide range show the distortion to be dependent upon the difference 
in the lengths of the two paths traveled by the sound and upon the distance from 
the speaker or the microphone to the reflecting surface. In speech records the 
amount of distortion is dependent upon the particular voice. One voice may have 
a frequency distribution such that with a given arrangement of reflector, micro- 
phone, and speaker, the intensity of the fundamental frequency is greatly reduced 
while the fundamental frequencies of other voices might not be affected by this 
particular condition. A small amount of distortion is introduced in cases where 
the ratio of the distances traveled by the reflected and direct sound is large. As 
this ratio decreases the distortion increases. 

MR. COFFMAN: The question was asked because within the last fortnight a 
scene came to my attention in which it was necessary to record dialog around a 
hard surface table. If the microphone had been placed relatively near the table, 
the distortion indicated in the demonstration would have been experienced, but 
by keeping the microphone near the camera, 15 feet distant from the table and 
the speakers, the recording quality was all that could be desired. 

MR. HUNT: I should like to emphasize two points which the experiment brings 
out: First, the advantage of being able to study these acoustical effects under 
laboratory control where one factor can be varied at a time. That was done in 



Oct., 1930] ONE TYPE OF ACOUSTIC DISTORTION 471 

this experiment. It was thus possible to subject this complicated acoustical 
situation to a quantitative study. The second point I want to bring out is that 
the experiments indicate quantitatively that under certain conditions there is an 
effect on the recorded sound quality depending on relative positions of the micro- 
phone and the reflecting surfaces near it. 

MR. RINGEL: In this interesting work, I believe it is important to consider 
the dimensions of the reflecting surfaces and of the sound radiating source as well 
as the separations between them and the microphone. The size of the source 
will determine to a great extent the directional radiation characteristics, while 
that of the walls will determine what wave-lengths will be reflected. It is theo- 
retically possible with a certain size of source, to so orient it as to obtain no 
reflection at all from the walls, the microphone receiving sound only from the 
loud speaker. This condition is determined by the relative size compared with 
the wave-length of the sound being used. In some practical cases on actual sets, 
use of a reflecting wall is advantageous in improving the high frequency response. 
At times, when one of the actors has his back to the microphone, I have had him 
speak at a more suitable angle to the walls of the set, so as to reflect the higher 
frequencies in his voice back to the microphone. Naturalness and intelligibility 
are thus oftentimes improved. 

MR. EVANS: It has been our experience that an orchestra recorded with mul- 
tiple microphones in a dead room sounds better than that recorded with a single 
microphone; there is more detail in the music and people prefer it. This is in 
line with Mr. Hanson's conclusions that multiple microphones in a dead room 
simulate room resonance. 

MR. HANSON: I cannot explain why you should obtain better quality with 
multiple microphones unless it is due to the fact that the distances from one 
microphone to the various instruments of the orchestra were such that a poor 
balance was obtained. Distortion caused by interference is less noticeable in 
music than in speech and might in this case be less objectionable than the loss of 
balance. 

MR. EVANS: We have done recording in a live room and one microphone is 
better than more than one. In a dead room, if you put in more than one, you get 
the same effect as in a live room with one microphone. 

MR. COFFMAN: Dr. Fletcher's film brings out that point. As will be recalled, 
the multiple reflections present in the case of speech were ruinous, but the music 
was even more pleasing. The cause is to be looked for in the realm of the psycho- 
logical. We like to feel that music fills the space in which it is created. Carnegie 
Hall in New York City has the reputation of being very good from the standpoint 
of musical acoustics, but it is reverberant; one has only to listen to the Phil- 
harmonic Orchestra playing there and then in the open-air Lemisohn Stadium to 
realize how much liveness contributes to our enjoyment of music. Multiple micro- 
phones in a dead room are a substitute for the reflecting surfaces necessary for 
the most satisfactory recording of music. 

MR. MAXFIELD: I have had no experience with the dead studios. In the case 
of live studios, I have never heard a record made with two microphones better 
than the best made with one. In the limited time allowed for setting up the 
orchestra and microphone you can get better results by using two equidistant 
microphones and letting them alone, meaning that when one is in a bad spot, 



472 R. L. HANSON 

the other probably isn't. When we have taken the time necessary to get the 
proper place for the one, we have had a better result. 

MR. Ross: With a large orchestra, a very large number of sound frequencies 
are being generated simultaneously and it is possible that this condition causes an 
accelerated decay of the reverberant sound actually preventing its reaching the 
microphones to produce distortion. For that reason it is possible to employ a 
number of these instruments for such recording. 

MR. KELLOGG: The question comes to mind in the course of the discussion 
as to why a reflecting surface doesn't bother us when listening direct. I have 
been playing with sound for a good many years, and I am just beginning to learn 
how much your sense of direction does for direct listening. You don't seem to 
hear in adequate magnitude sound from other sources than that from which it 
first comes. A very simple calculation based on the theory of comparisons in a 
room shows that if you have an unprotected source in a living room, six feet 
away, you get six times the energy reverberated around the room that you get from 
the source itself although the ear tells you the sound is coming from only one 
source. It fools you with regard to the amount of sound you are getting. It is 
interesting in a room where you have some noise to try the experiment of plugging 
one ear. I am convinced that one of the effects introduced is a marked rise in 
background noise. 



PRODUCTION ASPECTS OF A TECHNICAL LECTURE 
SOUND PICTURE 

FRANKLIN L. HUNT* 

The use of motion pictures for purposes of instruction had received 
the serious attention of educators prior to the advent of sound pictures, 
and collections of motion picture films on a wide variety of instruc- 
tional subjects had been made by government organizations and 
private institutions in this country and abroad. The recording of 
current events in newsreel form and films illustrating industrial 
processes are popular types of such pictures. Additional subjects 
prepared specifically for instruction in public schools and in advanced 
institutions of learning were also available. 

The addition of sound has greatly enhanced the possibilities of 
educational films, for the appeal not only to sight but also to hearing 
has greatly increased the effectiveness of this means of communicating 
ideas to the mind. However, sound pictures have so recently reached 
a state of practical development that their possibilities have not as 
yet been fully realized. This paper describes one which was recently 
recorded by the Bell Telephone Laboratories. It exemplifies the 
possibilities of sound picture films for technical instruction. 

The title of the film is Acoustic Principles of the Recording and 
Reproduction of Speech and Music by Dr. Harvey Fletcher of the Bell 
Telephone Laboratories. It presupposes a fairly advanced technical 
training on the part of those to whom it is presented and was intended 
primarily for the instruction of engineers. The subjects discussed 
in the order named are as follows: 

1 . The range of audibility of the ear. 

2. The effect of loudness of reproduction on the quality of speech. 

3. The effect of eliminating low and high frequencies from 
speech and music. 

4. The effect of resonance at different frequencies in the recording 
system on speech and music. 

* Bell Telephone Laboratories, New York. (Read before the Society at 
Washington ) 

473 



474 FRANKLIN L. HUNT [j. S. M. P. E. 

5. The effect of electrical overload in the recording system on 
speech and music. 

6. The effect of varying the speed of a sound record on speech 
and music. 

7. The effect of room reverberation on the quality of speech and 
music. 

The audibility range of the ear is discussed with the aid of the chart 
shown in Fig. 1, which gives the curves of minimum and maximum 
audibility plotted with intensities in bels as ordinates and pitch in 




FIG. 1. Auditory sensation area. 

octaves as abscissas. The piano scale was added to aid in inter- 
preting the pitch. The series of dots shown was used to illustrate 
the pitch and loudness of representative tones in the audible range. 
The corresponding tones were recorded at the time the pointer 
of the lecturer touched the various dots, by having an assistant 
simultaneously apply the requisite frequency, produced by an 
electrical oscillator, directly to the recording machine. 

The effect of reproducing speech at a higher power level than the 



Oct., 1930J 



TECHNICAL LECTURE SOUND PICTURE 



475 



original speech is to accentuate the low frequencies relative to the 
high and thus produce what is sometimes called a "boomy" effect. 
This is demonstrated with the aid of the chart shown in Fig. 2. 
While the lecturer described the experiment off stage an assistant 
pointed successively to the words "CONVERSATIONAL SPEECH" and 
"FALSE POSITION." The recording engineer simultaneously varied 
the power level at which the lecturer's voice was applied to the re- 
cording system, with the result that when reproduced, a part of the 
speech is natural in quality and at conversational level, and other 



5*4-3*2*1 R I 2 3 4 5 

i !! Hi II HI !i HI !! IB !! UH! HI H HI 




FIG. 2. Speech reproduction at normal and excessive power level. 

parts are very loud with accentuation of the low frequencies. 

The effect of eliminating low and high frequencies from speech 
and music is illustrated as shown in Figs. 3 and 4. While the lecturer 
spoke, or while the string quartet was playing, electrical filters were 
introduced between the recording microphone and the recorder to 
eliminate all frequencies below or above a series of predetermined 
values. These filters were switched into the recording system by 
an assistant who simultaneously signaled to a second assistant 
stationed at the side of the set, off scene, whose duty it was to push 




FIG. 3. Elimination of low frequencies from speech. 



FIG. 4. Elimination of high frequencies from music. 




-5-4-3-2-1 R I 2 3 4 5 

i n in n HI n in n in n HI n HI ii in 

PITCH-OCTAVES 




5-4-3-2-1 R I 2 3 

: n HI ii in ii in n in n HI ii inn in 

PITCH-OCTAVES 



4 5 



en 




-5-4-3-2-1 R I 2 3 4 5 

i n HI N HI ii in n m n HI n in it HI 

PITCH-OCTAVES 




5-4-3-2-1 R I 2 3 4 5 

IIIHflmtJniBIHBSIIIIIIIHI 

PITCH-OCTAVES 



FIG. 5. Effect of electrical resonance on speech. 




-5-4-3-2-1 R I 2 3 4 5 

IBBIBBIIIJJDODBinilllllll 

PITCH-OCTAVES 





5-4*3-2 -I R I 2 3 4 5 

lilMllllllRl 

PITCH-OCTAVES 



-5-4-3-2-1 R I 2 3 4 5 

iiHiHinininBfflnci 

PITCH-OCTAVES 




-5-4-3-2-1 R I 2 3 4 5 

I B Dl H III Hill B IH H ID UIH II PI 

PITCH-OCTAVES 



FIG. 6. Effect of electrical resonance on music. 



478 FRANKLIN L. HUNT fj. S. M. P, E. 

the black shield in and out to cover the corresponding parts of 
the audible range. To effect this, the chart* was made of two 
parallel boards, separated sufficiently to permit the black shield 
to slide between them. The front board had a large hole cut out at 
the center to conform to the auditory sensation area. The cross- 
section lines within this area were painted on the back board. These 
were therefore covered by the shield as it was pushed in by the assistant. 



NO RESONANCE 

mmmmmmmam 
RESONANCE AT ~2 3 




FIG. 7. Pre-scoring for the effect of resonance on music. 

To demonstrate the effect of resonance pre-scoring was used. 
Charts shown in Figs. 5 and 6, representing the different conditions 
of resonance, were made and another chart, shown in Fig. 7, listing 
the titles of the resonance charts was prepared. While the lecturer 
spoke off stage and again while the string quartet played off stage, 
an assistant pointed successively to one after another of the titles of 
Fig. 7. This chart was photographed while the speech or music 
record was being made. Simultaneously another assistant connected 

* This method of constructing the chart was suggested by Mr. W. B. Snow of 
the Bell Telephone Laboratories. 



Oct., 1930] 



TECHNICAL LECTURE SOUND PICTURE 



479 



into the recording system the corresponding resonance network so 
that the recorded sound effects were distorted in accordance with the 
indications of the pointer on the chart. Afterward enough footage 
of each of the charts shown in Figs. 5 and 6 was photographed to 
correspond to the several positions of the pointer in Fig. 7. These 
were substituted in the picture for the corresponding pointer indi- 
cations of chart 7. When the effects are reproduced the charts 
change instantly on the screen in synchronism with the changes of 




FIG. 8. Effect of electrical overload on music. 



the resonance frequencies in the music or speech which is reproduced 
simultaneously off scene. 

The effect of overload in the electrical system on speech is illus- 
trated by having an assistant switch from a normal to an over- 
loaded condition in the recording system while the lecturer indicated 
as he spoke which condition at the moment prevailed. The effect 
on music is illustrated with the aid of the chart shown in Fig. 8. 
While the string quartet played the lecturer pointed to the words 



480 FRANKLIN L. HUNT [j. S. M. P. E. 

"NORMAL" and "OVERLOADED" successively, and the assistant 
switched the circuits of the recording system correspondingly to 
give a normal or overloaded sound record. 

The effect of variations of speed of a sound record on the character 
of reproduced speech and music is illustrated with the aid of phono- 
graph records and the speed indicator shown in Fig. 9. Records 
of a woman's voice and of a full orchestra were used. The output 
of the phonograph reproducer was connected to the recording system. 
While the record was being played the speed indicator was simul- 




FIG. 9. Effect of speed variation on sound record. 

taneously photographed. An assistant varied the speed indicator 
first to increase its reading above normal, then to decrease it below 
normal, and finally to cause it to fluctuate about the normal position. 
At the same time, a second assistant changed the speed of the phono- 
graph turntable to correspond with the indications of the speed meter. 
When the picture of the speed meter is projected the speech or music 
simultaneously heard varies in pitch in accordance with the indica- 
tions of the speed meter. In this manner the voice of a woman 
was transformed from a high, almost inarticulate prattle to the 



Oct., 1930] TECHNICAL LECTURE SOUND PICTURE 481 

extremely slow enunciation of a deep bass and music was corre- 
spondingly distorted. The experiment clearly indicates that small 
fluctuations in speed produce a more displeasing effect on music 
than on speech. 

The effect of room reverberation is illustrated with the aid of the 
chart shown in Fig. 10. Phonograph records of a woman's voice 
and a full orchestra were used in this experiment. The effect of 
reverberation in a room was simulated by placing several phono- 
graph reproducers a few inches apart in the groove of a phonograph 




FIG. 10. Effect of reverberation on speech and music. 

record. * The phase differences of the several reproducers correspond 
to the multiple reflections obtained in a room with hard walls. The 
output of all the reproducers was combined in the sound record 
made. As the lecturer pointed successively to the condition of 
"REFLECTING WALLS" and "ABSORBING WALLS" an assistant switched 

* This method of artificially simulating reverberation was resorted to for 
emphasis but in practical sound picture recording it is usually not desirable to 
use artificial sound effects if these can be avoided. 



482 FRANKLIN L. HUNT [j. s. M. p. E. 

the output of several reproducers or of a single reproducer, respectively, 
into the recording system, thereby obtaining the effect of a room 
with reflecting walls or one which gave no reflections. This experi- 
ment brings out the fact that speech is more seriously affected by 
excessive reverberation than music. 

One other aspect of the technic of the picture may be worth 
mentioning. To make the charts clear and distinct they were painted 
in black and white on wood. It was thought that it would be awk- 
ward and distracting to have the charts changed on the scene. 
The subterfuge of projecting the speaker in close-up while introducing 
each successive experiment was therefore resorted to, to give an 
opportunity for the charts to be changed out of the picture, sup- 
posedly in the meantime. 

It is hoped that this lecture film may serve to indicate the manner 
in which rather complicated technical demonstrations can be handled 
with the aid of sound pictures. This is but one example of many 
more of similar type which will suggest themselves to those interested 
in the possibilities of sound pictures in the field of education. 

DISCUSSION 

MR. RINGEL: Mr. Fletcher and his associates are to be congratulated for 
turning out such a fine piece of work. In the film I was especially pleased to note 
an effect described in the first part of my paper. When Mr. Fletcher spoke from 
the foreground and then moved to the background, a change was produced. 
You noticed considerable loss in intelligibility, and the quality of his voice was 
not the same as his original voice. I am glad to have this point made clear. 

MR. HUNT: It is generally recognized that the most perfect articulation 
can be produced without reverberation, but it is necessary to have a certain 
amount for other effects. 

Mr. B. D. COOK: I believe the Bell Laboratories have always been very kind 
in passing on to the public the results of their tremendous expenditures in this 
pioneering work, and most of us have good cause to be grateful to them. I 
should like to have this film made available to laboratories throughout the coun- 
try in connection with the instruction of the younger men brought in year by year. 
If the purchase of this film is possible, it would help considerably, and I hope 
the Bell Laboratories will give this consideration. 

MR. SHEA: We hope that a limited distribution of this film may take place 
but it should be understood that our sound picture laboratory is not engaged in 
the production of films for general commercial distribution. The prime purpose 
of making such films as the Fletcher film in our laboratory is so that we may 
learn things we don't know about sound recording. 

MR. MAXFIEXD: In connection with the apparent loss of articulation, the 
amount of depth of this picture was exaggerated over and above the amount 
used in commercial recording. For the benefit of those interested in the amount 



Oct., 1930 J TECHNICAL LECTURE SOUND PICTURE 483 

of the loss for the depth effect I suggest that you see The Locked Door, Three 
Live Ghosts, Putting on the Ritz, The Bishop Murder Case, and Sweetie. They were 
all made that way. 

MR. Ross: In the overloading demonstration the sound level of the normal 
and overload appeared the same. If the whole system was overloaded why was 
not the overload demonstration at a higher level than the normal one? 

MR. HUNT: The volume levels in the recording machines were so arranged 
that there would not be an appreciable volume change between the normal and 
overloaded condition. 

MR. EVANS: In connection with Mr. Cook's statement that overloading some- 
times helps out, I am also of the opinion that this can occur. I have conducted 
tests of this kind hi connection with broadcasting. I had a loud speaker which 
could be switched from the output of the speech amplifiers to the monitoring 
rectifier on the end of the transmitter. It is obvious that the output of the loud 
speaker cannot be a faithful reproduction of the transmitter input. Blindfold 
tests have been made a number of times by a number of different people. In- 
variably they select the output of the radio transmitter as more satisfactory than 
the input. Apparently the explanation is that certain harmonics are produced by 
modulation or overloading which improve the pleasing reproduction of the sound. 



SOME CONSIDERATIONS AFFECTING THE DESIGN OF 
PHONOGRAPH NEEDLES 

R. T. FRIEBUS* 

However simple a piece of apparatus the phonograph needle 
appears to be, as a necessary link in the chain of reproducing equip- 
ment it must be as strong qualitatively as every other link, or the 
elementary principles of design are violated. One needs to calibrate 
only a few kinds of phonograph needles to find that quality of sound 
which has been achieved at the cost of thousands of dollars can be 
considerably impaired by using an improperly designed needle 
costing only a fraction of a cent. 

The purpose of this paper is to discuss some practical considerations 
about needles and to give data showing the relation between certain 
dimensions of the needle and its response-frequency characteristic. 

At the outset, in order to have a visual image of what we are 
discussing, Fig. 1 shows a photomicrograph of a recorded disk in 
profile with a needle placed in one of the grooves before playing. 
This illustrates the relative size of groove and needle, an important 
consideration as will be shown later. Fig. 2 shows the response- 
frequency curves of a few general types of needles. The response 
below 700 cycles is not shown since it is practically the same for all 
commercial needles. 

Curve D, Fig. 2, shows the response-frequency characteristic 
of a Western Electric 4-A reproducer and a standard commercial 
make of soft tone needle. We note that the response is materially 
down at 2000 cycles and rapidly decreases thereafter. The re- 
sponse of fiber needles also is somewhat similar. 

Curve C, Fig. 2, shows the response using a commercial medium 
tone needle. Here the gain begins to drop off at 3000 cycles, 
is 10 db. down at 4000 cycles, and is of very little use at 5000 
cycles. 

Curve B, Fig. 2, shows the response with the best needle now 

* Electrical Research Products, Inc., New York. (Read before the Society 
at Washington.) 
484 



DESIGN OF PHONOGRAPH NEEDLES 485 

available commercially. We note that this curve is quite satis- 
factory up to 4000 cycles and that at 5000 cycles the response is 
sufficient to have an effect upon the quality of speech and musical 
sounds. 

Curve A, Fig. 2, shows the response with an experimental needle. 
We note here that the flat part of the curve has been extended from 
3300 cycles to 4500 cycles and that the response at 5000 cycles is 
only slightly down. The frequency range for disk reproduction 
may be considered to have been increased approximately 700 cycles. 

Method of Testing. The data for these curves were obtained by 
using constant frequency records of known amplitudes to test the 
various needles in a Western Electric 4-A reproducer working into a 
500 ohm resistance load. 




FIG. 1. Photomicrograph of a recorded disk in profile with needle in groove. 

The electrical analogue of this elastic mechanical system is shown 
in Fig. 3 where the various constants indicated are the effective values 
measured at the needle point. From this sketch it can be shown 
that if the voltage developed shall be proportional to the transverse 
velocity of the record groove at all frequencies of interest, then the 
ratio, Fm/F, should remain constant. This condition can be stated 
mathematically as follows: * 

* ELMER, L. A., AND BLATTNER, D. G.: "Machine for Cutting Master Disk 
Records," Trans. Soc. Mot. Pict. Eng., XIII (May, 1929) No. 37, p. 227. 



486 



where 



Vm 
V 



R. T. FRIEBUS 

5 
(S + S d - 



[J. S. M. P. E. 



Rw 



s r 



In this equation the component, S n , of the stiffness factor, S, is the 
factor we are interested in. As S n is increased, 5 becomes greater; 



RESPONSE = 20* LOG 



WHERE e. IS 



VOLTAGE DEVELOPED ACROSS A LOAD 
RESISTANCE , FOR A NEEDLE POINT 
VELOCITY OFTTCM. PER SECOND. 

ZERO RESPONSE IS DEFINED AS ONE 
VOLT ACROSS A LOAD IMPEDANCE OF 
ONE OHM FOR A NEEDLE POINT 
VELOCITY OF ONE CM. PER SECOND. 



-60 




FREQUENCY IN CYCLES PER SECOND. 
FIG. 2. Response-frequency curves of several needle types. 

and as S becomes greater, the effect of the frequency terms, 

and j Rw have relatively less effect, and the ratio, Vm/ V, tends to 

remain more nearly constant. 

Structurally, the needle is a cantilever supported at the needle 
holder and loaded at the needle point. There are two sections 
of this cantilever that may be considered as critical. One is just 






Oct., 1930] 



DESIGN OF PHONOGRAPH NEEDLES 



487 



below the point of support where the total bending moment is 
greatest. The other is practically at the needle point where there 
are both sheer and bending. 

Wire. The size and stiffness of wire from which the needle is 
made determine whether there will be any decrease in response 
due to bending at, or just below, the needle holder. Response 
measurements on various sizes of wire from 0.035 to 0.075 inch, all 
with the same rate of taper of point, indicate that 0.070 inch wire 
safely takes care of the loads normally applied without showing 
attenuation due to bending at that section. Any increase beyond 
0.070 inch apparently yields no further benefit. 



TO AMPL. 



Si. 



RECORD 



n 

r i 


- Sr : 


m 
ISn R. 



V = GROOVE TRANSVERSE VELOCITY. 

Vm= ARMATURE VELOCITY. 

Vm/V=RATIO OF ARMATURE VELOCITY TO GROOVE TRANS. VELOCITY. 

m. = EFFECTIVE MASS OF ARMATURE AND NEEDLE. 

R = DAMPING RESISTANCE. 

FREQUENCY. 

2TTf. 

DIAPHRAGM STIFFNESS. 

STIFFNESS OF RECORD. 

STIFFNESS OF NEEDLE. 

SrSn. Vm S 

Sf+Sn, V (S + Si- ui 2 m)*jRw 

ALL VALUES EFFECTIVE AT GROOVE 

FIG. 3. Electrical analogue of the elastic mechanical system. 



f = 

V) 

sa = 

S r = 
S n = 

S = 



Taper. A series of tests were made on needles of uniform size 
wire to determine the effect of varying the rate of taper only. These 
tests indicate the fact that for loud tone needles the change in re- 
sponse due to the taper is limited to the high end of the frequency 
scale. Although soft tone needles appear to be an exception to this 
rule, their sharp taper extends so far back that in reality it may be 
considered as a change of wire size. It was further found that as 
the angle of taper is increased, the response is raised at 5000 cycles. 
The curve A, Fig. 2, was obtained when we reached 60 degrees. 



488 



R. T. FRIEBUS 



[J. S. M. P. E. 



However, a needle of any practicable wire size with a straight 60 
degree taper cannot be used for the reason that it quickly wears into 
the groove to a depth where its diameter is as great as the width of 
the groove. With further use it develops shoulders on the sides 
of the point which ride on the top of the groove. The point of the 
needle then rattles in the groove, producing a sound that may be 
characterized as fuzzy. 

Wear. Another point of interest in the design of needles is the 
change of quality as the point wears. Fig. 4 shows the shape of a 




FIG. 4. Shape of point after playing ten 16 in. 33Y 3 rpm. records. 

point which has been used in playing ten 16 in. 33 Vs rpm. records. 
Fig. 5, drawing A, shows the relative size of a needle point and a 
5000 cycle wave on the inside diameter, or beginning, of a 16 in. 
record and drawing B shows the same at the end. We note the 
round needle point is able to enter and follow the waves, how- 
ever short, in the beginning of a record. As the point progresses 
over the record, the length of the recorded waves increases in 
length due to the increasing linear speed. At the end a 5000 cycle 
wave has a length of 0.005 inch. It would be expected that the 
increasing length of the waves would compensate for the increase 



Oct., 1930] 



DESIGN OF PHONOGRAPH NEEDLES 



489 




45^7 
MINUTES OF PLAYING 



10 



Measured attenuation per minute. 



.0025 





FIG. 5. Relative size of point and 5000 cycle wave at inside diam- 
eter (4) and outside diameter (5) of a 16 in. record. 



490 R. T. FRIEBUS [J. S. M. p. E. 

in size of the point due to wear, but it appears that the needle wears 
considerably faster than the wave-length increases. The group 
of curves, Fig. 5, shows the measured attenuation per minute 
at 2000, 3000, 4000, and 5000 cycles. The amount of wear can, 
of course, be reduced by increasing the hardness of the point within 
certain limits; however, an excessively hard point will damage the 
record in a few playings. We have in progress tests of similar 
needles of varying degrees of hardness to establish an optimum 
value. The data are not as yet conclusive enough to be included 
in this paper. 

Attenuation is not the only phenomenon met in reproducing 
5000 cycle tones. It is obvious from drawing B that, whereas the 
5000 cycle note is recorded as a sine wave, the motion of the needle 
in attempting to follow the groove is not sinusoidal. The motion 
of the needle after it wears down is approximated in drawing B, 
by curves D and E from which it can be seen that the original sound 
is not accurately reproduced and that harmonic tones will be intro- 
duced. However, these harmonics are of the order of about 10,000 
cycles which are not reproduced by loud speakers ordinarily used. 

Curve D traces the actual motion of the needle if it followed 
one side of the groove, curve E shows the motion if it followed the 
other side. Obviously both sides cannot be followed at once; 
the result is that the needle rises and falls slightly in the groove, 
riding higher at the spots where the groove due to its curvature 
becomes too narrow for the flattened point. 

Scratch. A study of needles must necessarily include the relation 
between needle design and scratch noise. Electrical measure- 
ments of the amount of scratch noise made in a band of blank grooves 
recorded for the purpose indicate: 

(1) that there is no change of scratch noise with change in 
size of wire within the limits of the sizes found in good com- 
mercial needles; 

(2) that there is no change in scratch noise with the change 
of taper until we get down to the narrow tapers of the medium 
tone needle where there is also a noticeable loss in the quality 
of the sound itself ; 

(3) there is no change in scratch noise measured with 
needles of varying hardness. 

Shadowgraphing. That needles in packages be uniformly good is of 
considerable importance. Whereas a few bad needles in a package 



Oct., 1930 j 



DESIGN OF PHONOGRAPH NEEDLES 



491 



mean nothing to a person playing a phonograph at home, they 
are of considerable commercial importance to a motion picture 
exhibitor. They may cause a few bad performances with the 
corresponding bad impression on the patrons. This may be avoided 







FIG. 6. Shadowgraphs of needles from a new package not 100 
per cent factory inspected. 

if the manufacturer inspects each needle by means of a greatly 
enlarged silhouette called a shadowgraph and rejects the poor ones 
before they leave the factory. Needles that have been shadow- 
graphed are so labeled on the package. Fig. 6 shows a reproduction 



492 R. T. FRIEBUS [J. S. M. P. E 

of shadowgraphs of some needles taken from a new package which 
were not 100 per cent inspected at the factory. A is a good point, 
B is a flat point, C is a bent point, D is a broken point. 

In the foregoing, we have endeavored to show that needle design 
has a very definite influence on quality of reproduction, also the 
relation between performance and certain parameters of the needle 
such as diameter of wire, shape of point, and hardness of material 
at the point. 

We wish to express our indebtedness to Mr. W. S. Moody for his 
careful preparation of the many needles of special design with which 
much of these data were gotten. 

DISCUSSION 

MR. RUSSELL: I am wondering whether you have any data on fiber needles 
and whether they will drop off proportionately more than soft-surfaced ones. 
Have you any data on the cactus needle and also the sapphire or ball point needle? 

MR. FRIEBUS: The fiber needle response is similar to that of the soft tone 
needle, curve D, Fig. 2. It wears longer, but from the point of view of the re- 
production of sound in theaters its response at high frequencies is so low that it 
was not considered suitable. The cactus, also the Burmese, are similar to the 
fiber needle. We have used a diamond point, and at a high degree of taper found 
a high response all the way up to 5000 cycles, but considerable wear of the record 
is the result. 

MR. TAYLOR: Why is no mention made of the tungsten needle of the same 
diameter as the groove? How does this show up on comparison with the steel? 

MR. FRIEBUS: Such a needle after playing once would have a cross section 
at the point of bearing as shown in Fig. 5 in the bottom drawing, and the response 
would be indicated by the values at the end of the curves, Fig. 5, showing the 
attentuation per minute. I recall that the response-frequency curves of the 
tungsten point are very similar to curve B, which is a standard loud tone needle 

MR. TAYLOR: As I recall the figure, the length of the "canal boat" is greater 
than the diameter of the tungsten needle. 

MR. FRIEBUS: That diameter must be less than the width at the top of the 
groove which is 0.006 in. The length of the "canal boat" I have measured varies 
with hardness and runs between 0.004 and 0.006 in. Therefore, it could not be 
longer than in the case of the tungsten whose diameter is approximately 0.006 in 

MR. TAYLOR: Slightly more, on account of the angle. 

MR. FRIEBUS: Yes. 

PRESIDENT CRABTREE: The behavior of the needle is so closely associated 
with the nature of the record that it is difficult to mention one without the other 
Have any measurements been made on the resistance of the record to wear? 

MR. FRIEBUS: I rather hesitate speaking before the Society on that because 
I am not grounded, and it would be half guessing. I should like to be excused. 

MR. MILLER: The same surface scratch appeared on all needles. Why is that 
so? 



Oct., 1930] DESIGN OF PHONOGRAPH NEEDLES 493 

MR. FRIEBUS: My statement was that there was no change in scratch noise 
until we got a loss in quality itself which comes with the softer tone needles. 

MR. BRAUN: I should like to ask whether better results are obtained if the 
needle wears away more rapidly than the record and how rapidly should the needle 
wear as compared to wearing of the record for best reproduction? 

MR. FRIEBUS: I think that question involves the economics of the situation. 
With records for amateur playing of phonographs, companies are concerned with 
the wear of the record. For reproduction in theaters, the price of the record is 
such that they can be concerned more with quality than with wear on the record. 
There is no established standard of hardness for needles or records, and both 
divisions of the game are working in a medium that they think best fitted for 
their purpose. 

MR. BRAUN: I was referring to the 33 l /z rpm. records and my question 
might be put in this way, which is theoretically the proper needle, one which 
wears more quicky than the record or one which wears less rapidly ? 

MR. FRIEBUS: Theoretically, a needle which doesn't wear at all is best. 

MR. RUSSELL: If you have such a needle, then the record wears? 

MR. FRIEBUS: Yes. 

MR. RUSSELL: If that were true, a needle with the angle which was blunt or 
broad should give better quality than the soft needle. 

MR. FRIEBUS: The broader needle does. Curve A, Fig. 2, was obtained by 
using a needle of 60 degree taper, but it cannot be used commercially because 
the point, after a few minutes playing, wears a shoulder on itself and rattles in 
the groove giving a fuzzy sound. The cactus needle doesn't wear the record. 

MR. RUSSELL: Then with the cactus needle which also has a broad angle you 
may well get much of the quality without the wear on the record. 



IMPROVED SYNCHRONIZING APPARATUS FOR SIXTEEN 
MILLIMETER FILMS WITH DISK RECORDS 

WILLIAM H. BRISTOL* 

The purpose of this paper is to describe and demonstrate an 
improved synchronizing apparatus for 16 mm. films with disk records 
which in general may be attached to any 16 mm. projector without 
any change being required in the projector itself. 

The design of the synchronizing attachment is such that the 
projector may be operated in synchronism, with a disk record at 
either amateur speed of 16 frames per second or at a standard pro- 
fessional speed of 24 frames per second, the speed of the record disk 
in either case always being maintained at 33 Va revolutions per minute. 

In the present design the main idea has been to produce a portable 
outfit, compact, and of light weight, by which professional syn- 
chronized disk records may be reproduced in the home, school, 
church, club, etc., without in any way sacrificing the quality of the 
reproduced sound. 

The synchronizing apparatus is made up in two types, one where 
the turntable is mechanically connected to the projector by flexible 
shaft and another where the turntable is electrically connected to the 
projector by a pair of synchronizers, such as have been described in 
previous papers, which permit of resynchronizing the picture with 
the sound while it is being projected on the screen. 

In order to obtain perfect quality of reproduction of sound from 
disk records, it is absolutely necessary that the turntable revolve at a 
perfectly uniform speed and that it be practically free of any vibra- 
tion. Both of these requirements are more difficult to accomplish 
when the turntable is driven at standard synchronizing speed of 
33 Ys revolutions per minute than at the standard phonograph 
speed. 

For permanent installations as in theaters, the parts of the turn- 
table may be made massive with heavy flywheels to overcome 

* Wm. H. Bristol Talking Picture Corp., Waterbury, Conn. (Read before 
the Society at Washington.) 
494 



IMPROVED SYNCHRONIZING APPARATUS 



495 



vibration and variations in speed, but in a portable equipment, other 
expedients must be employed. 

In order to meet the requirements for a portable outfit, a special 
small high speed synchronous motor has been developed for driving 
both types of equipment. For the model which permits resyn- 
chronization, the synchronizers have also been greatly reduced in 
size. 

The complete turntable attachment for direct mechanical drive 
is shown in Fig. 1, which shows the motor, the worm and gear housing 




FIG. 1. Turntable attachment for direct mechanical drive. 

for driving the turntable, and a flexible shaft with a union joint at 
the end for conveniently making direct connection to any type of 
16 mm. projector. 

Two projecting drive shafts are provided at the gear housing, 
one of which will drive the projector at 16 frames per second and 
the other at 24 frames per second. The object of furnishing the two 
different drives has been to make the equipment capable of repro- 
ducing synchronized pictures which have been made at either of these 
speeds 



496 



WILLIAM H. BRISTOL 



[J. S. M. P. E. 



As described by the author in a previous paper, 35 mm. films 
which have been made at the standard speed of 24 frames per second 
may be optically reduced to 16 mm. width at the same time omitting 
every third frame, thus allowing for a synchronous projection at 
16 frames per second. Advantages of this method have been de- 
scribed in a previous paper. 

The turntable is driven by a vertical shaft shown in Fig. 1 which 
was described as follows in a previous paper: 




FIG. 2. Eastman Model B Kodascope with flexible shaft drive for 
synchronizing attachment. 



"It is of the utmost importance that the turntable be absolutely 
free of vibration in order to obtain perfect reproduction, especially 
of music. To accomplish this, we have developed a mechanical 
filter system which has proved very simple and efficient. It 
consists of mounting the turntable as shown, on a tripod, which 
stands on the floor independent of the base carrying the motors. 
A vertical shaft connecting the motors with the turntable is pro- 
vided with several flexible metal disk joints, designed particularly 



Oct., 1930] 



IMPROVED SYNCHRONIZING APPARATUS 



497 



to filter out the vibration that would otherwise be transmitted 
to the turntable from the motor base. 

"In addition to the flexible disk, there is a double sliding joint 
which is clearly shown in the illustration. This double sliding 
joint, working in conjunction with the flexible filter disks, has 
proved to be a most practical way of eliminating vibration, which 
is always present at the driving motor." 

In Fig. 2, an Eastman Model B self-threading projector is shown 




FIG. 3. Bell & Howell projector with flexible shaft attachment. 

with attached flexible shaft for making direct connection to the drive 
synchronizing attachment previously shown in Fig. 1. 

Fig. 3 shows a Bell and Howell projector with a flexible shaft 
attached ready for connection to the synchronizing unit. 

Fig. 4 shows an Ampro Superlite 16 mm. projector, with a flexible 
shaft for connection to the synchronizing unit. 

The complete turntabl^ unit for electrical synchronizing drive j 



498 



WILLIAM H. BRISTOL [j. s. M. P. E. 




FIG. 4. Ampro Superlite projector with flexible shaft attachment. 




FIG. 5. Complete turntable unit for electrical synchronizing drive. 



Oct., 1930] 



IMPROVED SYNCHRONIZING APPARATUS 



499 



shown in Fig. 5. The synchronous drive motor at the left drives 
the synchronizer through a shaft; current is generated by the syn- 
chronizer and through a small five wire cable drives the second 
synchronizer which furnishes the power to operate the projector. 

The field of the second synchronizer is provided with trunnion 
bearings for manual rotation of its field for resynchronizing as 
described in previous papers. 

This synchronizer which drives the projector is also provided 




FIG. 6. Resynchronizing attachment. 



with two projecting drive shafts. Through a short flexible con- 
nection one of these shafts drives the projector at 16 frames per second; 
the other is geared to drive the projector at 24 frames per second by 
simply changing the flexible connection. 

In Fig. 6, the resynchronizing element is shown mounted close 
to the projector for convenience of the operator. 

The turntable part of the unit used with the resynchronizing 
device may be located at any convenient distance from the projector, 



500 WILLIAM H. BRISTOL 

DISCUSSION 

PRESIDENT CRABTREE: What is the tolerance of synchronizing; suppose it is 
out fifty frames, can it be resynchronized quickly? 

MR. BRISTOL: Yes. There is one revolution for each frame, so that resyn- 
chronizing is a simple matter. 

PRESIDENT CRABTREE: Then it takes 50 turns of the handle? 

MR. BRISTOL: Yes, as rapidly as you can turn it, which takes about 10 seconds 
to resynchronize it. 

PRESIDENT CRABTREE: I should like to see you throw it out of synchronism 
and get it back as quickly as possible. (This was demonstrated.) 

MR. R. C. HUBBARD: I should like to ask Mr. Bristol if the negative was made 
on 35 mm. film. 

MR. BRISTOL: Yes, on 35 mm. and photographed at 24 frames per second, 
the same as professional pictures. We took this negative and put it on a special 
printer made so that it cuts out every third frame. In that way, we reduce the 
speed of the 16 mm. projector to its normal speed of 16 frames per second and 
still maintain synchronism. 

MR. EVANS : Does the motor of the projector run with the synchronized motor ? 

MR. BRISTOL: Yes, it runs so as to ventilate the lamp and at the same time 
do the work of driving the small projector. The other motor driving the turn- 
table is independent of this and is designed so that it runs at uniform speed with- 
out a governor. 

PRESIDENT CRABTREE : I think the experiment demonstrates that in the case 
of the dancing subject used, the picture and sound can be out of synchronism 
quite appreciably before it becomes objectionable. 

MR. W. B. COOK: In the projection of a slow motion picture, is the elimina- 
tion of the third frame obvious enough to show an apparent jump on the screen? 

MR. BRISTOL: No, it is less obvious than with normal speed pictures. 



THE MAINTENANCE OF SOUND FILM IN EXCHANGE 
OPERATION AND THE DEGREE THAT SOUND REPRO- 
DUCTION IS AFFECTED BY THE CONTINUED USE OF 
SOUND TRACK FILM 

TREVOR FAULKNER* 

The papers committee asked me to outline the results of my 
observations on the proper method of maintaining correct screening 
continuities and synchronization in the handling of sound film in 
exchange operation. I have also been asked to state my opinion 
of the effect that dirt, oil, and scratches accumulated in average 
projection runs on sound track prints have on sound reproduction. 

Of course, the exchange would like to furnish complete and un- 
spliced prints to every account. This, however, is quite impossible. 

Most black and white prints received by the exchange from the 
well equipped laboratory have no splices in them. The laboratory 
has printed and developed the film in one continuous strip, and from 
the beginning of the part titles down to the end of the end titles 
of each reel, each answer print is the exact duplicate of the master 
print in complete continuity down to the frame. If the negative is 
damaged in the laboratory and a few frames lost, either blank frames 
or duplicate frames are inserted in the negative so that all prints 
from that negative are exact duplicates in footage of the master 
print. Occasionally, the exchange receives prints that have one or 
two splices in them. The positive was damaged in printing, but in 
such cases a sufficient overlap is printed by the laboratory to permit 
a splice to be made without the loss of a single frame. 

In the laboratory, after the sample print has been approved, 
the negative is cut to fit it. Footage numbers are then placed on 
the margin of the cut negative, starting with the numeral zero at 
the picture start-mark and then appearing numerically at frequencies 
of every one foot or sixteen frames down to the end of each reel. 
These footage numbers are printed onto the margin of each positive 
print, thereby making it an easy task to check against the amount 

* Paramount Famous Lasky Corporation, New York City. 

501 



502 TREVOR FAULKNER [j. s. M. P. E. 

of footage of any deletion where a splice does occur, and inasmuch as 
these marginal footage numbers occur at the identical frame of every 
print of the same subject, the insertion of replacement parts is a 
simple task. 

A number of these distributing companies which are furnishing 
film to the exhibitor so that he may reproduce the sound from either 
sound-track film or the synchronized disks, according to the type 
of equipment he may have, are having their entire quota of sound 
film printed with the sound on the film. The sound is also recorded 
on synchronized disks to fit these prints. This procedure makes it 
possible to serve a maximum number of accounts with sound track 
prints at the time of the peak demand for a subject, and then as 
many prints with sound track as necessary are converted into syn- 
chronized disk prints by splicing in film where it may have been 
deleted until the complete footage equals the footage of the original 
film and each scene is synchronized with the disk record. 

It is, of course, necessary that the projection equipment through 
which these converted prints are projected be equipped with a mask 
at the side of the aperture, to keep the sound track from being 
projected onto the screen. However, the fact that sound track prints 
can be converted into synchronized disk prints has meant an 
enormous saving in the laboratory cost of printing, and has made 
available to the theater which has only the disk equipment many 
subjects which otherwise would not be made in disk form. The cost 
of printing additional synchronized prints with full screen width 
photography over and above the quota of sound track prints would 
not be consistent with the revenue derived from disk equipment 
only, in many instances. 

At the time prints of a subject are received in an exchange, it is 
essential that all reels of these prints have a close inspection, and 
if any splices do occur in the film they should be checked by inspection 
of the marginal footage numbers appearing on each side of the 
splice to determine if there is any film removed. As closely following 
the printing of a release as is possible, the exchanges should be fur- 
nished with positive information as to the footage of each reel of 
that release. This information should come to them in the form of a 
correct continuity sheet which is descriptive of the scenes and the 
definite footage of them and the dialog that they contain. In addi- 
tion, the exchanges should be furnished with riders that are to be 
attached to the in and out cards of each print of that subject, which 



Oct., 1930] SOUND FILM IN EXCHANGE OPERATION 503 

carry the exact footage and frames of film in each reel between the 
picture start-mark and the end of the first scene that ends without 
a fade-out or a dissolve. 

Repairing of a film while it is being served to the sound track 
accounts can often be done by deletion, providing the sound track 
on the film removed does not contain any dialog or rather any 
essential words in a dialog. A close inspection of the sound track 
modulations will usually reveal whether the sound is speech or music, 
and a check-up with the dialog continuity sheet will show whether 
the part which it is necessary to remove is important. A replace- 
ment can be ordered if the continuity of the dialog is interrupted. 

A sound track print thus handled will come up to the time that 
it is to be converted into a synchronized disk print with a number 
of splices in it. Most splices that are in these prints before they 
are converted will appear between the picture start-mark and the 
first scene of action in the reel, as some projectionists will insist 
on mounting two thousand feet of film onto one reel. In doing this 
they remove the ends of the reels, from the last scene of action down 
to the end of the reel and from the beginning of the following reel 
down to the first scene of action, and join the two actions together 
in order to reduce the number of machine cut-overs in their evening's 
program. This practice of mounting more than one thousand feet 
of film onto one reel is prohibited by the fire ordinances in some cities, 
is banned by some of the larger theater operating chains, and should 
be discouraged by everyone in tb \ industry. It changes the reel 
assembly for the distributor in many cases; there is the loss of 
important film where the projectionist fails to return it to the ex- 
change; there are mix-ups in the consecutive arrangement of the 
reels in following shows where the projectionist has erred in affixing 
the part titles on their respective reels ; and it makes it most difficult 
to retain the reel in proper condition to be converted into a syn- 
chronized disk print. In addition, when film is scratched or other- 
wise damaged by passing through a projector that is so damaging it, 
the amount of damaged film is usually in proportion to the amount 
of film footage mounted on the reel being projected. 

Up until a sound track print is converted into a synchronized 
disk print, it should not be booked to a disk account because of the 
probable lack of synchronization between it and its accompanying 
disk, due to the few frames that may have been removed at various 
places without any reinsertion of film to make up for the loss of 



504 TREVOR FAULKNER [J. S. M. P. E. 

footage. Before a print is converted, as I have already said, the 
exchange can make deletions that do not interrupt the dialog con- 
tinuity or make the action jumpy without replacing film to make 
up for the loss in footage. But the splice where the two ends are 
brought together should be one that could be identified by quick 
inspection as an exchange splice. The inspector should stop at 
every splice and if it is an exchange splice, then it is reasonable to 
suppose that the inspector who made the splice has approved any 
missing footage as all right. 

At the time that a print is converted into a synchronized disk 
print, a very careful check-up of every splice must be made and re- 
placements inserted at every point where there is any footage missing 
in order to bring the print to its original footage to the frame. 
After the print is converted the original footage must be maintained 
so long as it is booked, and when splices are made replacement film 
must be inserted to make up for the lost frames. Where it is possible 
these replacements should always be made from the exact duplicate 
scenes as those damaged. It is possible for the distributor to have 
some centralized point, from where the actual desired scenes and 
footage can be air-mailed to the exchanges when needed, thus effect- 
ing no more than a twenty-four hour delay in the transaction. 

Where a synchronized disk film is damaged at intervals and re- 
placement parts of the actual scenes damaged are not available, 
and it is necessary to insert black leader into the footage, the 
necessary footage should be made up in the fewest practical number 
of insertions. For example, if there were ten different places in a 
close sequence where it was necessary to remove two frames each, 
and there was no definite close-up or dialog in this footage, it would 
be better to place all twenty frames in at one point than have the ten 
different black places flashed across the screen. In so doing, though, 
the inspector must realize in the following inspections of that film 
that the regularity of the marginal footage numbers will be dis- 
turbed throughout this sequence. The method of putting replace- 
ment film all in at one place is always desirable in making replace- 
ments in the leader between the start-mark and the first action of a 
reel and is not important on the main title of the first reel. As 
there is no synchronized dialog or effects during the footage of the 
main title, there should be no dark spots on the screen whatsoever 
in the first reel of any subject prior to the first scene of action. Any 
insertions of black film in the main title to maintain the original 



Oct., 1930] SOUND FILM IN EXCHANGE OPERATION 505 

correct footage should be ahead of the point where the title fades in 
on the screen. 

After a print has been converted into a synchronized disk print, 
it must not be booked for showing in a sound track theater, as any 
black leader that may be in this print will affect the sound repro- 
duction to such an extent that it will either cause dissatisfaction or 
the projectionist will remove it prior to its screening. This will 
cause additional work when the print is returned to the exchange 
and considerable more loss of footage in inserting replacement film 
again before the print can be used for synchronized disk book- 
ings. 

In maintaining disk film in the exchange, every time that a splice 
is made it should be stamped with an embossing stamp to show that 
the footage is complete, thereby removing the necessity of a check-up 
on the footage in following inspections. This materially speeds up 
following inspections. Contrary to the opinion that prevailed at 
the beginning of sound, it is not necessary to block out splices made 
in sound track film, providing these splices are accurately scraped 
and cut. The splice, however, if improperly scraped will be heard 
when it passes before the photo-cell. 

Under the proper average care the physical life of sound track 
film is greater than its booking life ; and after it is converted into a 
synchronized disk print, if it receives proper care and an adequate 
replacement follow-up is observed, the desired condition of having 
a complete satisfactory print for every account can be realized. 

It would not be consistent to make any definite statement con- 
cerning the number of times that a sound track print or synchronized 
disk print is projected before it is in an unfit condition for further 
screening. At least any number so stated would not fit the two 
different kinds of film. In practically all cases, projection equip- 
ment that reproduces sound from the film is new and is under the 
care of skilled and competent projectionists. Consequently the 
minimum amount of damage would result in its screening. The 
status of equipment which reproduces sound from synchronized 
disks is usually such that film used in it would have much shorter 
life than sound track film. 

Prior to sound, one could more or less accurately state the pro- 
jection life of a print, due to the fact that we did not then have to 
consider deletions and splices which now retire film quicker than 
any other factors. A few frames, an entire scene, and sometimes a 



506 TREVOR FAULKNER [J. s. M. P. E. 

complete sequence removed from a silent print would hardly classify 
it as unserviceable for some of the smaller accounts so long as the 
titles were of sufficient length to be read, there was a fade-out at 
the ending, and the physical condition of the remaining part of the 
print was fair. Now, however, no theater wired for sound is going 
to be reconciled to screening sound track film where the dialog 
continuity is interrupted, or synchronized disk prints that have too 
much black leader in them or that are out of synchronization with 
the disk. It behooves the distributor, therefore, to retire film from 
service now which would have been classified as being in fair physical 
condition in the days before sound. 

A fair average, however, of the number of times a sound track 
print can be run before the normal wear and tear on it would put it 
in a questionable condition could be placed at two hundred times. 
Give the average print two hundred screenings and the damage to it 
will include warped and buckled film (caused by the loss of moisture 
from the heat of the projection lamps), dirty and oily surfaces, and 
surface scratches on both the celluloid and gelatin sides. The 
average film that has been run two hundred times will show very 
little strain on the sprocket perforations. Distributors that use the 
utmost care in their exchange maintenance of film will find that 
fully seventy-five per cent of the film that is returned to them from 
the field for final disposition will be in good physical condition so 
far as sprocket perforations are concerned. This is due to a combi- 
nation of improved conditions of projection equipment; a better 
knowledge of the equipment and its operation by the projectionist; 
a far greater regard for film conditions; increased bookings of 
multiple date screenings and fewer bookings of the one day runs; 
a more organized inspection department in the exchange backed by 
the desire of the exchange manager to have this department func- 
tioning as nearly one hundred per cent efficiently as is possible. 

From my observations on the effect of repeated screenings on the 
quality of sound reproduced from the sound track, I would say that 
there is no apparent tonal difference between the first time a sound 
track print is screened and the two hundredth time, providing, of 
course, that the sound track surfaces are entirely free from dirt, 
oil, or any other foreign substance, that the film is not warped or 
buckled, that the sprocket perforations are not enlarged, and that 
there are no scratches or sprocket tooth marks on the sound track 
surfaces. Any oil, dirt, or other foreign substances that might be 



Oct., 1930] SOUND FILM IN EXCHANGE OPERATION 507 

on the surfaces of the sound track will cause a decrease in the volume 
of the sound reproduced therefrom in proportion to the amount 
of light that is thereby obstructed from reaching the photo-cell 
pick-up. Also a gathering of dirt, wax, or other foreign substances 
at the light valve directly between the exciter lamp and the photo- 
cell pick-up will cause a decrease in volume in the reproduction of the 
sound in proportion to the amount of light that this obstruction keeps 
from filtering through from the exciter lamp to the photo-cell pick- 
up. Dirt or oil on the film or lodged in the sound aperture will 
have a tendency to affect tonal reproduction to that extent that these 
agencies might vary the light intensity in the photo-cell pick-up. 
Warped and buckled film will affect the tonal reproduction of sound 
only if the film is twisted sufficiently for its smooth passage over 
the sound aperture to be disturbed. If the sound track weaves to 
the right or left of its regular tread as it passes over the sound aper- 
ture, the volume is decreased in proportion to the amount of the 
sound modulations that do not pass in a direct line between the 
exciter lamp and the photo-cell pick-up. There would also be the 
inclination toward tonal distortion if the film were so badly warped 
and twisted that the sound modulations were not permitted to ride 
across the sound aperture at the correct cross angle. This above 
condition would also prevail where the sprocket perforations are 
enlarged sufficiently to permit the weaving of the film in its passage 
over the sound aperture. Minor scratches on the sound track of 
Western Electric recorded sound do not have any noticeable effect 
on the sound reproduction. Where the scratch is wide enough and 
the surface is dark, if there are no abrasions causing the emulsion 
to be entirely removed from the celluloid, the only effect in the sound 
reproduction would be a decrease in the volume of sound in pro- 
portion to the amount of the area of the sound track that the dark- 
ened scratch would cover. Where there are pin point abrasions in 
the emulsion at intervals in the scratch, there will be a tendency 
to reproduce a sputtering noise very much like that of radio static ; 
and wherever the light valves of the sound modulations are altered, 
the tonal reproduction will be affected. 

If the scratch is deep and the emulsion is entirely removed over 
the area of scratch, it will cause a ground noise where the light 
from the exciter lamp is filtered through the uncovered celluloid 
onto the photo-cell pick-up. This ground noise would be without 
tone if the edges of the emulsion are removed with a razor-like 



508 TREVOR FAULKNER 

precision, but if the edges of the scratch are ragged or irregular, it 
would reproduce noises other than straight ground noise. 

A scratch on the celluloid side of the sound track will not affect 
the sound reproduction unless it is made in such a manner that it 
will deflect the light rays from the exciter lamp and change their 
values in the photo-cell pick-up. 

Where the sprocket perforations approach the sound track through 
faulty printing, or the focus of the exciter lamp is such that its 
rays are not confined to the width of that sound track, but are 
spread over the area of the perforations or the frame line between 
the frames of action in the picture, we shall have a sound reproduced 
very similar to a motor boat exhaust. This sound is also reproduced 
by sprocket tooth marks on the sound track where there are abra- 
sions in the emulsion. 

The answer to the problem of exchange maintenance of sound 
film is to make replacement of damaged film with the actual scenes 
where possible and to withdraw the film from further service when 
it approaches an unsatisfactory condition because of splices, deletions, 
warping and buckling, scratches, and a weakened condition. 

When film is so withdrawn from service, it is my opinion that 
the general average will show that that print has about two hundred 
screenings to its credit. 



THE SOVIET CINEMATOGRAPHY 

L. I. MONOSSON* 

Before speaking about the Soviet cinema and the Soviet cinema 
industry, I want to say a few words about the cinema of pre -revolu- 
tionary Russia. 

There were six studios in Moscow, one in Leningrad, two in Yalta, 
Crimea, and two in Odessa; in other words, the pre-revolutionary 
film industry of Russia had four producing bases. 

The peculiarity of the Soviet film studios, as compared with the 
pre-revolutionary ones, is the building of the studios in the different 
National Republics for national cinema production. 

The character of the film productions in pre-revolutionary Russia 
corresponded to that in other countries before 1914. During the 
war the Russian cinema was utilized in the same manner as in other 
countries at that time. 

Most of the cinema theaters were small but in the larger cities 
there were especially built cinema theaters, some of them with seating 
capacities up to 1000. The building of new cinema theaters pro- 
ceeded very slowly and during the war was discontinued altogether. 
In the provincial towns the cinema theaters were ill adapted for 
their purpose, with a limited number of seats and other disadvantages, 
reminding one of the provincial cinema houses in other countries. 

Since it is our aim here to discuss the Soviet cinematography 
dating from 1917, I shall not dwell any longer on the Russian 
cinematography prior to that time. 

I will attempt first of all to explain briefly the essence of the Soviet 
cinematography which is in many respects different from the cine- 
matography of other countries, both as to form and content. I 
will begin with the artistic trends in the Soviet cinematography. 

Art Trends in the Soviet Cinema. Cinematography, like every 
domain of art, should be considered in its context of cultural, social, 
and political standards prevalent at the given period. The form 
and style of a film are closely bound with its subject matter which, 

* Amkino Corp., New York. (Read before the Society at Washington.) 

509 



510 L. I. MONOSSON [j. s. M. P. E. 

in turn, is determined by the demands of the times. The cinema- 
tography of pre-revolutionary Russia conformed both in content 
and form to the tastes and manners of its public. True, it had no 
command of the technic that would raise the art of the screen to the 
formal levels of other arts, yet the screen of that time, too, responded 
to the influences of esthetic symbolism and nebulous romanticism 
that held sway over the literature of the period; there were experi- 
menters who sought the proper form that would best give expression 
to this kind of subject matter. 

The early Soviet cinematography, like other arts, could not at 
first find its proper thematic content nor the clear cut forms to shape 
the new material. Some guiding principles were arrived at both as 
to form and subject matter, but it took quite some time before the 
individual artists, the directors, scenario writers, and actors assimi- 
lated the new reality, the new born standards, the new principles 
of coordination of film and spectator. It was only after the civil 
war, with the return to peace time reconstruction, that problems 
of art and culture received their due share of public attention. 
By that time the artist already began to sense his true relationship 
to the social organism, and the role of the artist in the multiform 
process of reconstruction has become more or less clearly defined. 

A period of technical experimentation and achievement brought 
with it also a pretty well crystallized conception of the ideological 
and artistic fundamentals of the Soviet cinematography. To begin 
with, the social aspect of life was to receive preference before the 
individualistic aspect. Man was to be portrayed not in terms of 
his inner personal moods and emotions but in terms of his social 
relationships. The drama of the individual in conflict with the 
individual gave place to the drama of conflict between groups, 
between social strata, or between individuals representing these 
socially antagonistic groups. 

On its formal side, too, certain basic tenets became crystallized. 
A maximum of expressiveness, of contact with the spectator was 
considered as paramount, and to this end the new regisseurs bent 
all of their effort. Not halftones and evanescent shadings, but vivid, 
sharp sequences, eloquent contrasts, overtones of montage, capti- 
vating tempo were made the basis of the new cinematic idiom. 

The new film actor followed as a corollary to the new film. The 
actor was emancipated from his enslavement to the "psychological" 
drama and the screen was emancipated from the overlordship of 



Oct., 1930] THE SOVIET CINEMATOGRAPHY 511 

the actor. No longer was the film regarded as a "vehicle" for the 
actor, but quite the contrary the actor took his proper place as a 
component element of the picture. 

The artistic aspect of the Soviet cinema requires a reference to the 
distinctive styles of some of the outstanding Soviet directors whose 
fame and artistic influence have gone far beyond the boundaries of 
their country. One of them is Sergei Eisenstein, an acknowledged 
world master in the realm of the cinema, the director of Potemkin, 
Ten Days That Shook the World, and Old and New. Eisenstein bases 
his pictures not upon individual heroes but on the masses of humanity. 
Individual characters figure in his films only as episodic material. 
A brilliant and convincing example of this method is his Potemkin, 
also his Ten Days, two films that won not only the admiration but 
also the close study and emulation of film-masters the world over. 
The Eisenstein School has many followers among the workers in the 
Soviet cinema. His methods are being widely applied and his style 
emulated by the new crop of film directors. 

Another regisseur of creative genius is Vsevolod Pudovkin, director 
of The End of St. Petersburg, Mother, and Storm over Asia. Unlike 
Eisenstein, he draws upon fiction for the story of his films, but his 
fiction is of the stupendous proportion and dynamic sweep of a social 
drama, and in this genre Pudovkin is a great master, indeed. The 
vivid quality of his emotional methods, his robust realism mark 
Pudovkin as unique in his art. 

The style of both of these master-regisseurs has been influenced 
to an extent by the American masters of the early Griffith and Chaplin 
period, as well as by some French master innovators. 

To the list of serious original and highly talented Soviet regisseurs 
must be added the name of Alexander Dovzhenko ; director of 
Arsenal, Earth, and other notable films. Dovzhenko is Ukrainian 
and works in terms of Ukrainian subject matter but along the ar- 
tistic tenets established by the leading masters of the Soviet cinema. 

An interesting group of cinema workers are the so-called Feks 
(initials for "Factory of Experimental Actors"). They work in the 
genre of expressionist melodrama. Their original taste and sense 
of style go together with a sound sense of the cinema. One of their 
best pictures is The New Babylon. 

In addition to the regisseurs and "schools" here mentioned as 
characteristic of the Soviet cinematography, there are also a number 
of regisseurs excelling in the traditional realistic style not unmixed 



512 L. I. MONOSSON [j. s. M. P. E. 

with modern innovations and influences. Tarich, the director of 
Czar Ivan the Terrible, and Protozanov, director of Lash of the Czar, 
belong to this category. 

It may be noted that nearly all of the best products of the Soviet 
cinematography of recent years have been exhibited in the United 
States not in the luxurious movie palaces, it is true, but before 
discriminating and appreciative audiences. The Soviet films shown 
in the United States received high and merited praise from the 
American film critics. 

Distribution and Exhibition. The technical, economical, and 
organizational basis of the Soviet cinema industry have also distinc- 
tive features. I will first take up distribution and exhibition: 

The potentiality for distribution and exhibition of films in the 
various republics of the Soviet Union, whose territory is 23,342,872 
square kilometers with a population of 147,013,600, is as follows: 

Republic Percentage 
Russian Soc. Feder. Soviet Rep. 68.5 

Ukrainian Soc. Soviet Rep. 22.0 

Trans-Caucasian Soviet Rep. 5 . 

Central Asiatic Soviet Rep. 3 . 9 

White Russian Soviet Rep 1 . 5 

The distribution is conducted on the basis of a rigid schedule of rates 
for the various types of cinema establishments that have a pro- 
jection apparatus and a more or less permanent exhibition place. 
The latest data covering the Russian Socialist Federated Soviet 
Republic show that on October last this republic, the population 
of which is upward of one hundred millions, was served by a net 
of 9693 cinema establishments divided into the following types: 

Number of 

Type of Cinema Establishment Establishments Percentage 
Cinema theaters (in towns, cities, and 

urban settlements) 860 8.8 

Clubs for workers and state employees 1997 20 . 6 
Schools of all types, children's homes, 

and colonies 224 2.3 

Theater clubs 888 9.2 

Cinema theaters in rural settlements 1114 11.4 

Traveling outfits for rural service 3873 40 . 4 

Miscellaneous 246 2.6 

Thus rural establishments serving the rural population constitute 



Oct., 1930 J THE SOVIET CINEMATOGRAPHY 513 

51.4 per cent of the entire cinema net in the largest republic of the 
Union. If we added to this the number of establishments serving 
the workers' clubs, we see that the greatest number of cinema estab- 
lishments serves the needs of the workers and the peasants. 

The urban cinema theaters account for only 8.8 per cent of the 
total number of cinema establishments. The urban population of 
RSFSR numbers 15,979,440. The seating capacity